engineering mathematics -...

Engineering Mathematics

In memory of Elizabeth

Engineering MathematicsFourth Edition

JOHN BIRD, BSc(Hons) CMath, FIMA, CEng, MIEE, FCollP, FIIE

NewnesOXFORD AMSTERDAM BOSTON LONDON NEW YORK PARIS

SAN DIEGO SAN FRANCISCO SINGAPORE SYDNEY TOKYO

NewnesAn imprint of Elsevier ScienceLinacre House, Jordan Hill, Oxford OX2 8DP200 Wheeler Road, Burlington MA 01803

First published 1989Second edition 1996Reprinted 1998 (twice), 1999Third edition 2001Fourth edition 2003

Copyright 2001, 2003, John Bird. All rights reserved

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Contents

Preface xi

Part 1 Number and Algebra 1

1 Revision of fractions, decimals andpercentages 11.1 Fractions 11.2 Ratio and proportion 31.3 Decimals 41.4 Percentages 7

2 Indices and standard form 92.1 Indices 92.2 Worked problems on indices 92.3 Further worked problems on

indices 112.4 Standard form 132.5 Worked problems on standard

form 132.6 Further worked problems on standard

form 14

3 Computer numbering systems 163.1 Binary numbers 163.2 Conversion of binary to decimal 163.3 Conversion of decimal to binary 173.4 Conversion of decimal to binary via

octal 183.5 Hexadecimal numbers 20

4 Calculations and evaluation offormulae 244.1 Errors and approximations 244.2 Use of calculator 264.3 Conversion tables and charts 284.4 Evaluation of formulae 30

Assignment 1 33

5 Algebra 345.1 Basic operations 345.2 Laws of Indices 365.3 Brackets and factorisation 385.4 Fundamental laws and precedence 405.5 Direct and inverse proportionality 42

6 Further algebra 446.1 Polynomial division 446.2 The factor theorem 466.3 The remainder theorem 48

7 Partial fractions 517.1 Introduction to partial fractions 517.2 Worked problems on partial fractions

with linear factors 517.3 Worked problems on partial fractions

with repeated linear factors 547.4 Worked problems on partial fractions

with quadratic factors 55

8 Simple equations 578.1 Expressions, equations and

identities 578.2 Worked problems on simple

equations 578.3 Further worked problems on simple

equations 598.4 Practical problems involving simple

equations 618.5 Further practical problems involving

simple equations 62

Assignment 2 64

9 Simultaneous equations 659.1 Introduction to simultaneous

equations 659.2 Worked problems on simultaneous

equations in two unknowns 659.3 Further worked problems on

simultaneous equations 679.4 More difficult worked problems on

simultaneous equations 699.5 Practical problems involving

simultaneous equations 70

10 Transposition of formulae 7410.1 Introduction to transposition of

formulae 7410.2 Worked problems on transposition of

formulae 7410.3 Further worked problems on

transposition of formulae 7510.4 Harder worked problems on

transposition of formulae 77

11 Quadratic equations 8011.1 Introduction to quadratic equations 8011.2 Solution of quadratic equations by

factorisation 80

vi CONTENTS

11.3 Solution of quadratic equations bycompleting the square 82

11.4 Solution of quadratic equations byformula 84

11.5 Practical problems involving quadraticequations 85

11.6 The solution of linear and quadraticequations simultaneously 87

12 Logarithms 8912.1 Introduction to logarithms 8912.2 Laws of logarithms 8912.3 Indicial equations 9212.4 Graphs of logarithmic functions 93

Assignment 3 94

13 Exponential functions 9513.1 The exponential function 9513.2 Evaluating exponential functions 9513.3 The power series for ex 9613.4 Graphs of exponential functions 9813.5 Napierian logarithms 10013.6 Evaluating Napierian logarithms 10013.7 Laws of growth and decay 102

14 Number sequences 10614.1 Arithmetic progressions 10614.2 Worked problems on arithmetic

progression 10614.3 Further worked problems on arithmetic

progressions 10714.4 Geometric progressions 10914.5 Worked problems on geometric

progressions 11014.6 Further worked problems on geometric

progressions 11114.7 Combinations and permutations 112

15 The binomial series 11415.1 Pascals triangle 11415.2 The binomial series 11515.3 Worked problems on the binomial

series 11515.4 Further worked problems on the

binomial series 11715.5 Practical problems involving the

binomial theorem 120

16 Solving equations by iterativemethods 12316.1 Introduction to iterative methods 12316.2 The NewtonRaphson method 12316.3 Worked problems on the

NewtonRaphson method 123

Assignment 4 126

Multiple choice questions on chapters 1 to16 127

Part 2 Mensuration 131

17 Areas of plane figures 13117.1 Mensuration 13117.2 Properties of quadrilaterals 13117.3 Worked problems on areas of plane

figures 13217.4 Further worked problems on areas of

plane figures 13517.5 Worked problems on areas of

composite figures 13717.6 Areas of similar shapes 138

18 The circle and its properties 13918.1 Introduction 13918.2 Properties of circles 13918.3 Arc length and area of a sector 14018.4 Worked problems on arc length and

sector of a circle 14118.5 The equation of a circle 143

19 Volumes and surface areas ofcommon solids 14519.1 Volumes and surface areas of

regular solids 14519.2 Worked problems on volumes and

surface areas of regular solids 14519.3 Further worked problems on volumes

and surface areas of regularsolids 147

19.4 Volumes and surface areas of frusta ofpyramids and cones 151

19.5 The frustum and zone of a sphere 15519.6 Prismoidal rule 15719.7 Volumes of similar shapes 159

20 Irregular areas and volumes and meanvalues of waveforms 16120.1 Areas of irregular figures 16120.2 Volumes of irregular solids 16320.3 The mean or average value of a

waveform 164

Assignment 5 168

Part 3 Trigonometry 171

21 Introduction to trigonometry 17121.1 Trigonometry 17121.2 The theorem of Pythagoras 17121.3 Trigonometric ratios of acute

angles 172

CONTENTS vii

21.4 Fractional and surd forms oftrigonometric ratios 174

21.5 Solution of right-angled triangles 17521.6 Angles of elevation and

depression 17621.7 Evaluating trigonometric ratios of any

angles 17821.8 Trigonometric approximations for small

angles 181

22 Trigonometric waveforms 18222.1 Graphs of trigonometric functions 18222.2 Angles of any magnitude 18222.3 The production of a sine and cosine

wave 18522.4 Sine and cosine curves 18522.5 Sinusoidal form A sint 18922.6 Waveform harmonics 192

23 Cartesian and polar co-ordinates 19423.1 Introduction 19423.2 Changing from Cartesian into polar

co-ordinates 19423.3 Changing from polar into Cartesian

co-ordinates 19623.4 Use of R ! P and P ! R functions on

calculators 197

Assignment 6 198

24 Triangles and some practicalapplications 19924.1 Sine and cosine rules 19924.2 Area of any triangle 19924.3 Worked problems on the solution of

triangles and their areas 19924.4 Further worked problems on the

solution of triangles and theirareas 201

24.5 Practical situations involvingtrigonometry 203

24.6 Further practical situations involvingtrigonometry 205

25 Trigonometric identities andequations 20825.1 Trigonometric identities 20825.2 Worked problems on trigonometric

identities 20825.3 Trigonometric equations 20925.4 Worked problems (i) on trigonometric

equations 21025.5 Worked problems (ii) on trigonometric

equations 21125.6 Worked problems (iii) on trigonometric

equations 212

25.7 Worked problems (iv) on trigonometricequations 212

26 Compound angles 21426.1 Compound angle formulae 21426.2 Conversion of a sint C b cost into

R sint C ) 21626.3 Double angles 22026.4 Changing products of sines and cosines

into sums or differences 22126.5 Changing sums or differences of sines

and cosines into products 222

Assignment 7 224

Multiple choice questions on chapters 17to 26 225

Part 4 Graphs 231

27 Straight line graphs 23127.1 Introduction to graphs 23127.2 The straight line graph 23127.3 Practical problems involving straight

line graphs 237

28 Reduction of non-linear laws to linearform 24328.1 Determination of law 24328.2 Determination of law involving

logarithms 246

29 Graphs with logarithmic scales 25129.1 Logarithmic scales 25129.2 Graphs of the form y D axn 25129.3 Graphs of the form y D abx 25429.4 Graphs of the form y D aekx 255

30 Graphical solution of equations 25830.1 Graphical solution of simultaneous

equations 25830.2 Graphical solution of quadratic

equations 25930.3 Graphical solution of linear and

quadratic equations simultaneously263

30.4 Graphical solution of cubic equations264

31 Functions and their curves 26631.1 Standard curves 26631.2 Simple transformations 26831.3 Periodic functions 27331.4 Continuous and discontinuous

functions 27331.5 Even and odd functions 27331.6 Inverse functions 275

Assignment 8 279

viii CONTENTS

Part 5 Vectors 281

32 Vectors 28132.1 Introduction 28132.2 Vector addition 28132.3 Resolution of vectors 28332.4 Vector subtraction 284

33 Combination of waveforms 28733.1 Combination of two periodic

functions 28733.2 Plotting periodic functions 28733.3 Determining resultant phasors by

calculation 288

Part 6 Complex Numbers 291

34 Complex numbers 29134.1 Cartesian complex numbers 29134.2 The Argand diagram 29234.3 Addition and subtraction of complex

numbers 29234.4 Multiplication and division of complex

numbers 29334.5 Complex equations 29534.6 The polar form of a complex

number 29634.7 Multiplication and division in polar

form 29834.8 Applications of complex numbers 299

35 De Moivres theorem 30335.1 Introduction 30335.2 Powers of complex numbers 30335.3 Roots of complex numbers 304

Assignment 9 306

Part 7 Statistics 307

36 Presentation of statistical data 30736.1 Some statistical terminology 30736.2 Presentation of ungrouped data 30836.3 Presentation of grouped data 312

37 Measures of central tendency anddispersion 31937.1 Measures of central tendency 31937.2 Mean, median and mode for discrete

data 31937.3 Mean, median and mode for grouped

data 32037.4 Standard deviation 32237.5 Quartiles, deciles and percentiles 324

38 Probability 32638.1 Introduction to probability 32638.2 Laws of probability 326

38.3 Worked problems on probability 32738.4 Further worked problems on

probability 32938.5 Permutations and combinations 331

39 The binomial and Poisson distribution 33339.1 The binomial distribution 33339.2 The Poisson distribution 336

Assignment 10 339

40 The normal distribution 34040.1 Introduction to the normal distribution

34040.2 Testing for a normal distribution 344

41 Linear correlation 34741.1 Introduction to linear correlation 34741.2 The product-moment formula for

determining the linear correlationcoefficient 347

41.3 The significance of a coefficient ofcorrelation 348

41.4 Worked problems on linearcorrelation 348

42 Linear regression 35142.1 Introduction to linear regression 35142.2 The least-squares regression lines 35142.3 Worked problems on linear

regression 352

43 Sampling and estimation theories 35643.1 Introduction 35643.2 Sampling distributions 35643.3 The sampling distribution of the

means 35643.4 The estimation of population

parameters based on a large samplesize 359

43.5 Estimating the mean of a populationbased on a small sample size 364

Assignment 11 368

Multiple choice questions on chapters 27to 43 369

Part 8 Differential Calculus 375

44 Introduction to differentiation 37544.1 Introduction to calculus 37544.2 Functional notation 37544.3 The gradient of a curve 37644.4 Differentiation from first

principles 377

CONTENTS ix

44.5 Differentiation of y D axn by thegeneral rule 379

44.6 Differentiation of sine and cosinefunctions 380

44.7 Differentiation of eax and ln ax 382

45 Methods of differentiation 38445.1 Differentiation of common functions

38445.2 Differentiation of a product 38645.3 Differentiation of a quotient 38745.4 Function of a function 38945.5 Successive differentiation 390

46 Some applications of differentiation 39246.1 Rates of change 39246.2 Velocity and acceleration 39346.3 Turning points 39646.4 Practical problems involving maximum

and minimum values 39946.5 Tangents and normals 40346.6 Small changes 404

Assignment 12 406

Part 9 Integral Calculus 407

47 Standard integration 40747.1 The process of integration 40747.2 The general solution of integrals of the

form axn 40747.3 Standard integrals 40847.4 Definite integrals 411

48 Integration using algebraic substitutions41448.1 Introduction 41448.2 Algebraic substitutions 41448.3 Worked problems on integration using

algebraic substitutions 41448.4 Further worked problems on integration

using algebraic substitutions 41648.5 Change of limits 416

49 Integration using trigonometricsubstitutions 41849.1 Introduction 41849.2 Worked problems on integration of

sin2 x, cos2 x, tan2 x and cot2 x 41849.3 Worked problems on powers of sines

and cosines 42049.4 Worked problems on integration of

products of sines and cosines 42149.5 Worked problems on integration using

the sin substitution 422

49.6 Worked problems on integration usingthe tan substitution 424

Assignment 13 425

50 Integration using partial fractions 42650.1 Introduction 42650.2 Worked problems on integration using

partial fractions with linearfactors 426

50.3 Worked problems on integration usingpartial fractions with repeated linearfactors 427

50.4 Worked problems on integration usingpartial fractions with quadraticfactors 428

51 The t =q

2substitution 430

51.1 Introduction 430

51.2 Worked problems on the t D tan 2

substitution 43051.3 Further worked problems on the

t D tan 2

substitution 432

52 Integration by parts 43452.1 Introduction 43452.2 Worked problems on integration by

parts 43452.3 Further worked problems on integration

by parts 436

53 Numerical integration 43953.1 Introduction 43953.2 The trapezoidal rule 43953.3 The mid-ordinate rule 44153.4 Simpsons rule 443

Assignment 14 447

54 Areas under and between curves 44854.1 Area under a curve 44854.2 Worked problems on the area under a

curve 44954.3 Further worked problems on the area

under a curve 45254.4 The area between curves 454

55 Mean and root mean square values 45755.1 Mean or average values 45755.2 Root mean square values 459

56 Volumes of solids of revolution 46156.1 Introduction 46156.2 Worked problems on volumes of solids

of revolution 461

x CONTENTS

56.3 Further worked problems on volumesof solids of revolution 463

57 Centroids of simple shapes 46657.1 Centroids 46657.2 The first moment of area 46657.3 Centroid of area between a curve and

the x-axis 46657.4 Centroid of area between a curve and

the y-axis 46757.5 Worked problems on centroids of

simple shapes 46757.6 Further worked problems on centroids

of simple shapes 46857.7 Theorem of Pappus 471

58 Second moments of area 47558.1 Second moments of area and radius of

gyration 47558.2 Second moment of area of regular

sections 47558.3 Parallel axis theorem 47558.4 Perpendicular axis theorem 47658.5 Summary of derived results 47658.6 Worked problems on second moments

of area of regular sections 47658.7 Worked problems on second moments

of areas of composite areas 480

Assignment 15 482

Part 10 Further Number and Algebra 483

59 Boolean algebra and logic circuits 48359.1 Boolean algebra and switching circuits

48359.2 Simplifying Boolean expressions 48859.3 Laws and rules of Boolean algebra

488

59.4 De Morgans laws 49059.5 Karnaugh maps 49159.6 Logic circuits 49559.7 Universal logic circuits 500

60 The theory of matrices and determinants50460.1 Matrix notation 50460.2 Addition, subtraction and multiplication

of matrices 50460.3 The unit matrix 50860.4 The determinant of a 2 by 2 matrix

50860.5 The inverse or reciprocal of a 2 by 2

matrix 50960.6 The determinant of a 3 by 3 matrix

51060.7 The inverse or reciprocal of a 3 by 3

matrix 511

61 The solution of simultaneous equations bymatrices and determinants 51461.1 Solution of simultaneous equations by

matrices 51461.2 Solution of simultaneous equations by

determinants 51661.3 Solution of simultaneous equations

using Cramers rule 520

Assignment 16 521

Multiple choice questions on chapters 4461522

Answers to multiple choice questions 526

Index 527

Preface

This fourth edition of Engineering Mathematicscovers a wide range of syllabus requirements. Inparticular, the book is most suitable for the latestNational Certificate and Diploma courses andVocational Certificate of Education syllabuses inEngineering.

This text will provide a foundation in mathematicalprinciples, which will enable students to solve mathe-matical, scientific and associated engineering princi-ples. In addition, the material will provide engineer-ing applications and mathematical principles neces-sary for advancement onto a range of IncorporatedEngineer degree profiles. It is widely recognised thata students ability to use mathematics is a key elementin determining subsequent success. First year under-graduates who need some remedial mathematics willalso find this book meets their needs.

In Engineering Mathematics 4th Edition, theoryis introduced in each chapter by a simple outline ofessential definitions, formulae, laws and procedures.The theory is kept to a minimum, for problem solv-ing is extensively used to establish and exemplifythe theory. It is intended that readers will gain realunderstanding through seeing problems solved andthen through solving similar problems themselves.

For clarity, the text is divided into ten topicareas, these being: number and algebra, mensura-tion, trigonometry, graphs, vectors, complex num-bers, statistics, differential calculus, integral calculusand further number and algebra.

This new edition will cover the following syl-labuses:

(i) Mathematics for Technicians, the core unitfor National Certificate/Diploma courses inEngineering, to include all or part of thefollowing chapters:

1. Algebra: 2, 4, 5, 813, 17, 19, 27, 302. Trigonometry: 18, 21, 22, 243. Statistics: 36, 374. Calculus: 44, 46, 47, 54

(ii) Further Mathematics for Technicians,the optional unit for National Certifi-cate/Diploma courses in Engineering, toinclude all or part of the following chapters:

1. Algebraic techniques: 10, 14, 15,2830, 34, 5961

2. Trigonometry: 2224, 263. Calculus: 4449, 52584. Statistical and probability: 3643

(iii) Applied Mathematics in Engineering, thecompulsory unit for Advanced VCE (for-merly Advanced GNVQ), to include all orpart of the following chapters:

1. Number and units: 1, 2, 42. Mensuration: 17203. Algebra: 5, 8114. Functions and graphs: 22, 23, 275. Trigonometry: 21, 24

(iv) Further Mathematics for Engineering, theoptional unit for Advanced VCE (formerlyAdvanced GNVQ), to include all or part ofthe following chapters:

1. Algebra and trigonometry: 5, 6,1215, 21, 25

2. Graphical and numerical techniques:20, 22, 2631

3. Differential and integral calculus:4447, 54

(v) The Mathematics content of Applied Sci-ence and Mathematics for Engineering,for Intermediate GNVQ

(vi) Mathematics for Engineering, for Founda-tion and Intermediate GNVQ

(vii) Mathematics 2 and Mathematics 3 for City& Guilds Technician Diploma in Telecom-munications and Electronic Engineering

(viii) Any introductory/access/foundation co-urse involving Engineering Mathematics atUniversity, Colleges of Further and Highereducation and in schools.

Each topic considered in the text is presented ina way that assumes in the reader little previousknowledge of that topic.

xii ENGINEERING MATHEMATICS

Engineering Mathematics 4th Edition providesa follow-up to Basic Engineering Mathematicsand a lead into Higher Engineering Mathemat-ics.

This textbook contains over 900 workedproblems, followed by some 1700 furtherproblems (all with answers). The further problemsare contained within some 208 Exercises; eachExercise follows on directly from the relevantsection of work, every two or three pages. Inaddition, the text contains 234 multiple-choicequestions. Where at all possible, the problemsmirror practical situations found in engineeringand science. 500 line diagrams enhance theunderstanding of the theory.

At regular intervals throughout the text are some16 Assignments to check understanding. For exam-ple, Assignment 1 covers material contained inChapters 1 to 4, Assignment 2 covers the materialin Chapters 5 to 8, and so on. These Assignmentsdo not have answers given since it is envisaged that

lecturers could set the Assignments for students toattempt as part of their course structure. Lecturersmay obtain a complimentary set of solutions of theAssignments in an Instructors Manual availablefrom the publishers via the internet full workedsolutions and mark scheme for all the Assignmentsare contained in this Manual, which is available tolecturers only. To obtain a password please [email protected] with the following details:course title, number of students, your job title andwork postal address.

To download the Instructors Manual visithttp://www.newnespress.com and enter the booktitle in the search box, or use the following directURL: http://www.bh.com/manuals/0750657766/

Learning by Example is at the heart of Engi-neering Mathematics 4th Edition.

John Bird

University of Portsmouth

Part 1 Number and Algebra

1

Revision of fractions, decimalsand percentages

1.1 Fractions

When 2 is divided by 3, it may be written as 23 or2/3. 23 is called a fraction. The number above theline, i.e. 2, is called the numerator and the numberbelow the line, i.e. 3, is called the denominator.

When the value of the numerator is less thanthe value of the denominator, the fraction is calleda proper fraction; thus 23 is a proper fraction.When the value of the numerator is greater thanthe denominator, the fraction is called an improperfraction. Thus 73 is an improper fraction and can alsobe expressed as a mixed number, that is, an integerand a proper fraction. Thus the improper fraction 73is equal to the mixed number 2 13 .

When a fraction is simplified by dividing thenumerator and denominator by the same number,the process is called cancelling. Cancelling by 0 isnot permissible.

Problem 1. Simplify1

3C 2

7

The lowest common multiple (i.e. LCM) of the twodenominators is 3 7, i.e. 21

Expressing each fraction so that their denomina-tors are 21, gives:

1

3C 2

7D 1

3 7

7C 2

7 3

3D 7

21C 6

21

D 7 C 621

D 1321

Alternatively:

1

3C 2

7D

Step (2)#

7 1 C

Step (3)#

3 221"

Step (1)

Step 1: the LCM of the two denominators;

Step 2: for the fraction 13 , 3 into 21 goes 7 times,7 the numerator is 7 1;

Step 3: for the fraction 27 , 7 into 21 goes 3 times,3 the numerator is 3 2.

Thus1

3C 2

7D 7 C 6

21D 13

21as obtained previously.

Problem 2. Find the value of 32

3 21

6

One method is to split the mixed numbers intointegers and their fractional parts. Then

32

3 21

6D(

3 C 23

)(

2 C 16

)

D 3 C 23

2 16

D 1 C 46

16

D 136

D 112

Another method is to express the mixed numbers asimproper fractions.

2 ENGINEERING MATHEMATICS

Since 3 D 93

, then 32

3D 9

3C 2

3D 11

3

Similarly, 21

6D 12

6C 1

6D 13

6

Thus 32

3 21

6D 11

3 13

6D 22

6 13

6D 9

6D 11

2

as obtained previously.

Problem 3. Determine the value of

45

8 31

4C 12

5

45

8 31

4C 12

5D 4 3 C 1C

(5

8 1

4C 2

5

)

D 2 C 5 5 10 1 C 8 240

D 2 C 25 10 C 1640

D 2 C 3140

D 23140

Problem 4. Find the value of3

7 14

15

Dividing numerator and denominator by 3 gives:1 3

7 14

15 5D 1

7 14

5D 1 14

7 5Dividing numerator and denominator by 7 gives:

1 14 21 7 5

D 1 21 5 D

25

This process of dividing both the numerator anddenominator of a fraction by the same factor(s) iscalled cancelling.

Problem 5. Evaluate 13

5 21

3 33

7

Mixed numbers must be expressed as improperfractions before multiplication can be performed.Thus,

13

5 21

3 33

7

D(

5

5C 3

5

)(

6

3C 1

3

)(

21

7C 3

7

)

D 85

1 7

1 3 24

8

7 1D 8 1 8

5 1 1D 64

5D 124

5

Problem 6. Simplify3

7 12

21

3

7 12

21D

3

712

21

Multiplying both numerator and denominator by thereciprocal of the denominator gives:

3

712

21

D

1 3

1 7 21

3

12 41 12

1 21 21

1

12 1

D3

41

D 34

This method can be remembered by the rule: invertthe second fraction and change the operation fromdivision to multiplication. Thus:

3

7 12

21D

1 3

1 7 21

3

12 4D 3

4as obtained previously.

Problem 7. Find the value of 53

5 71

3

The mixed numbers must be expressed as improperfractions. Thus,

53

5 71

3D 28

5 22

3D14 28

5 3

22 11D 42

55

Problem 8. Simplify

1

3(

2

5C 1

4

)(

3

8 1

3

)

The order of precedence of operations for problemscontaining fractions is the same as that for inte-gers, i.e. remembered by BODMAS (Brackets, Of,Division, Multiplication, Addition and Subtraction).Thus,

1

3(

2

5C 1

4

)(

3

8 1

3

)

REVISION OF FRACTIONS, DECIMALS AND PERCENTAGES 3

D 13

4 2 C 5 120

31

24 8(B)

D 13

135 20

82

1(D)

D 13

265

(M)

D 5 1 3 2615

(S)

D 7315

D 41315

Problem 9. Determine the value of7

6of(

31

2 21

4

)C 51

8 3

16 1

2

7

6of(

31

2 21

4

)C 51

8 3

16 1

2

D 76

of 11

4C 41

8 3

16 1

2(B)

D 76

54

C 418

316

12

(O)

D 76

54

C 411 8

162

3 1

2(D)

D 3524

C 823

12

(M)

D 35 C 65624

12

(A)

D 69124

12

(A)

D 691 1224

(S)

D 67924

D 28 724

Now try the following exercise

Exercise 1 Further problems on fractions

Evaluate the following:

1. (a)1

2C 2

5(b)

7

16 1

4[(a)

9

10(b)

3

16

]

2. (a)2

7C 3

11(b)

2

9 1

7C 2

3[(a)

43

77(b)

47

63

]

3. (a) 103

7 82

3(b) 3

1

4 44

5C 15

6[(a) 1

16

21(b)

17

60

]

4. (a)3

4 5

9(b)

17

35 15

119[(a)

5

12(b)

3

49

]

5. (a)3

5 7

9 12

7(b)

13

17 4 7

11 3 4

39[(a)

3

5(b) 11

]

6. (a)3

8 45

64(b) 1

1

3 25

9[(a)

8

15(b)

12

23

]

7.1

2C 3

5 8

15 1

3

[1

7

24

]

8.7

15of(

15 57

)C(

3

4 15

16

) [5

4

5

]

9.1

4 2

3 1

3 3

5C 2

7

[ 13

126

]

10.(

2

3 11

4

)(

2

3C 1

4

)C 13

5

[2

28

55

]

1.2 Ratio and proportion

The ratio of one quantity to another is a fraction, andis the number of times one quantity is contained inanother quantity of the same kind. If one quantity isdirectly proportional to another, then as one quan-tity doubles, the other quantity also doubles. When aquantity is inversely proportional to another, thenas one quantity doubles, the other quantity is halved.

Problem 10. A piece of timber 273 cmlong is cut into three pieces in the ratio of 3to 7 to 11. Determine the lengths of the threepieces


The total number of parts is 3 C 7 C 11, that is, 21.Hence 21 parts correspond to 273 cm

1 part corresponds to273

21D 13 cm

3 parts correspond to 3 13 D 39 cm7 parts correspond to 7 13 D 91 cm

11 parts correspond to 11 13 D 143 cm

i.e. the lengths of the three pieces are 39 cm,91 cm and 143 cm.

(Check: 39 C 91 C 143 D 273)

Problem 11. A gear wheel having 80 teethis in mesh with a 25 tooth gear. What is thegear ratio?

Gear ratio D 80:25 D 8025

D 165

D 3.2

i.e. gear ratio D 16 : 5 or 3.2 : 1

Problem 12. An alloy is made up ofmetals A and B in the ratio 2.5 : 1 by mass.How much of A has to be added to 6 kg ofB to make the alloy?

Ratio A : B: :2.5 : 1 (i.e. A is to B as 2.5 is to 1)

orA

BD 2.5

1D 2.5

When B D 6 kg, A6

D 2.5 from which,

A D 6 2.5 D 15 kg

Problem 13. If 3 people can complete atask in 4 hours, how long will it take 5people to complete the same task, assumingthe rate of work remains constant

The more the number of people, the more quicklythe task is done, hence inverse proportion exists.

3 people complete the task in 4 hours,

1 person takes three times as long, i.e.

4 3 D 12 hours,

5 people can do it in one fifth of the time that

one person takes, that is12

5hours or 2 hours

24 minutes.


Exercise 5 Further problems on ratio andproportion

1. Divide 621 cm in the ratio of 3 to 7 to 13.[81 cm to 189 cm to 351 cm]

2. When mixing a quantity of paints, dyes offour different colours are used in the ratioof 7:3:19:5. If the mass of the first dyeused is 3 12 g, determine the total mass ofthe dyes used. [17 g]

3. Determine how much copper and howmuch zinc is needed to make a 99 kgbrass ingot if they have to be in theproportions copper : zinc: :8 : 3 by mass.

[72 kg : 27 kg]

4. It takes 21 hours for 12 men to resurfacea stretch of road. Find how many menit takes to resurface a similar stretch ofroad in 50 hours 24 minutes, assumingthe work rate remains constant. [5]

5. It takes 3 hours 15 minutes to fly fromcity A to city B at a constant speed. Findhow long the journey takes if

(a) the speed is 1 12 times that of theoriginal speed and

(b) if the speed is three-quarters of theoriginal speed.

[(a) 2 h 10 min (b) 4 h 20 min]

1.3 Decimals

The decimal system of numbers is based on thedigits 0 to 9. A number such as 53.17 is calleda decimal fraction, a decimal point separating theinteger part, i.e. 53, from the fractional part, i.e. 0.17


A number which can be expressed exactly asa decimal fraction is called a terminating deci-mal and those which cannot be expressed exactlyas a decimal fraction are called non-terminatingdecimals. Thus, 32 D 1.5 is a terminating decimal,but 43 D 1.33333. . . is a non-terminating decimal.1.33333. . . can be written as 1.P3, called one point-three recurring.

The answer to a non-terminating decimal may beexpressed in two ways, depending on the accuracyrequired:

(i) correct to a number of significant figures, thatis, figures which signify something, and

(ii) correct to a number of decimal places, that is,the number of figures after the decimal point.

The last digit in the answer is unaltered if the nextdigit on the right is in the group of numbers 0, 1,2, 3 or 4, but is increased by 1 if the next digiton the right is in the group of numbers 5, 6, 7, 8or 9. Thus the non-terminating decimal 7.6183. . .becomes 7.62, correct to 3 significant figures, sincethe next digit on the right is 8, which is in the groupof numbers 5, 6, 7, 8 or 9. Also 7.6183. . . becomes7.618, correct to 3 decimal places, since the nextdigit on the right is 3, which is in the group ofnumbers 0, 1, 2, 3 or 4.

Problem 14. Evaluate42.7 C 3.04 C 8.7 C 0.06

The numbers are written so that the decimal pointsare under each other. Each column is added, startingfrom the right.

42.73.048.70.06

54.50

Thus 42.7Y 3.04Y 8.7Y 0.06 = 54.50

Problem 15. Take 81.70 from 87.23

The numbers are written with the decimal pointsunder each other.

87.2381.70

5.53

Thus 87.23 81.70 = 5.53

Problem 16. Find the value of23.4 17.83 57.6 C 32.68

The sum of the positive decimal fractions is

23.4 C 32.68 D 56.08The sum of the negative decimal fractions is

17.83 C 57.6 D 75.43Taking the sum of the negative decimal fractionsfrom the sum of the positive decimal fractions gives:

56.08 75.43i.e. 75.43 56.08 D 19.35

Problem 17. Determine the value of74.3 3.8

When multiplying decimal fractions: (i) the numbersare multiplied as if they are integers, and (ii) theposition of the decimal point in the answer is suchthat there are as many digits to the right of it as thesum of the digits to the right of the decimal pointsof the two numbers being multiplied together. Thus

(i) 74338

5 94422 290

28 234

(ii) As there are 1 C 1 D 2 digits to the right ofthe decimal points of the two numbers beingmultiplied together, (74.3 3.8), then

74.3 3.8 = 282.34

Problem 18. Evaluate 37.81 1.7, correctto (i) 4 significant figures and (ii) 4 decimalplaces


37.81 1.7 D 37.811.7

The denominator is changed into an integer bymultiplying by 10. The numerator is also multipliedby 10 to keep the fraction the same. Thus

37.81 1.7 D 37.81 101.7 10 D

378.1

17

The long division is similar to the long division ofintegers and the first four steps are as shown:

22.24117..

17)

378.10000034

3834

4134

7068

20

(i) 37.81 1.7 = 22.24, correct to 4 significantfigures, and

(ii) 37.81 1.7 = 22.2412, correct to 4 decimalplaces.

Problem 19. Convert (a) 0.4375 to a properfraction and (b) 4.285 to a mixed number

(a) 0.4375 can be written as0.4375 10 000

10 000without changing its value,

i.e. 0.4375 D 437510 000

By cancelling

4375

10 000D 875

2000D 175

400D 35

80D 7

16

i.e. 0.4375 =716

(b) Similarly, 4.285 D 4 2851000

D 4 57200

Problem 20. Express as decimal fractions:

(a)9

16and (b) 5

7

8

(a) To convert a proper fraction to a decimal frac-tion, the numerator is divided by the denomi-nator. Division by 16 can be done by the longdivision method, or, more simply, by dividingby 2 and then 8:

4.50

2)

9.00

0.5625

8)

4.5000

Thus,916

= 0.5625

(b) For mixed numbers, it is only necessary toconvert the proper fraction part of the mixednumber to a decimal fraction. Thus, dealingwith the 78 gives:

0.875

8)

7.000i.e.

7

8D 0.875

Thus 578

= 5.875


Exercise 3 Further problems on decimals

In Problems 1 to 6, determine the values ofthe expressions given:

1. 23.6 C 14.71 18.9 7.421 [11.989]2. 73.84 113.247 C 8.21 0.068

[31.265]3. 3.8 4.1 0.7 [10.906]4. 374.1 0.006 [2.2446]5. 421.8 17, (a) correct to 4 significant

figures and (b) correct to 3 decimalplaces.

[(a) 24.81 (b) 24.812]

6.0.0147

2.3, (a) correct to 5 decimal places

and (b) correct to 2 significant figures.[(a) 0.00639 (b) 0.0064]


7. Convert to proper fractions:

(a) 0.65 (b) 0.84 (c) 0.0125 (d) 0.282and (e) 0.024[

(a)13

20(b)

21

25(c)

1

80(d)

141

500(e)

3

125

]

8. Convert to mixed numbers:

(a) 1.82 (b) 4.275 (c) 14.125 (d) 15.35and (e) 16.2125

(a) 1

41

50(b) 4

11

40(c) 14

1

8

(d) 157

20(e) 16

17

80

In Problems 9 to 12, express as decimal frac-tions to the accuracy stated:

9.4

9, correct to 5 significant figures.

[0.44444]

10.17

27, correct to 5 decimal place.

[0.62963]

11. 19

16, correct to 4 significant figures.

[1.563]

12. 1331

37, correct to 2 decimal places.

[13.84]

1.4 Percentages

Percentages are used to give a common standardand are fractions having the number 100 as their

denominators. For example, 25 per cent means25

100

i.e.1

4and is written 25%.

Problem 21. Express as percentages:(a) 1.875 and (b) 0.0125

A decimal fraction is converted to a percentage bymultiplying by 100. Thus,

(a) 1.875 corresponds to 1.875 100%, i.e.187.5%

(b) 0.0125 corresponds to 0.0125 100%, i.e.1.25%

Problem 22. Express as percentages:

(a)5

16and (b) 1

2

5

To convert fractions to percentages, they are (i) con-verted to decimal fractions and (ii) multiplied by 100

(a) By division,5

16D 0.3125, hence 5

16corre-

sponds to 0.3125 100%, i.e. 31.25%

(b) Similarly, 12

5D 1.4 when expressed as a

decimal fraction.

Hence 12

5D 1.4 100% D 140%

Problem 23. It takes 50 minutes to machinea certain part. Using a new type of tool, thetime can be reduced by 15%. Calculate thenew time taken

15% of 50 minutes D 15100

50 D 750100

D 7.5 minutes.hence the new time taken is

50 7.5 D 42.5 minutes.

Alternatively, if the time is reduced by 15%, thenit now takes 85% of the original time, i.e. 85% of

50 D 85100

50 D 4250100

D 42.5 minutes, as above.

Problem 24. Find 12.5% of 378

12.5% of 378 means12.5

100 378, since per cent

means per hundred.

Hence 12.5% of 378 D 12.51

100 8 378 D 1

8 378 D

378

8D 47.25


Problem 25. Express 25 minutes as apercentage of 2 hours, correct to thenearest 1%

Working in minute units, 2 hours D 120 minutes.Hence 25 minutes is

25

120ths of 2 hours. By can-

celling,25

120D 5

24

Expressing5

24as a decimal fraction gives 0.208P3

Multiplying by 100 to convert the decimal fractionto a percentage gives:

0.208P3 100 D 20.8P3%Thus 25 minutes is 21% of 2 hours, correct to thenearest 1%.

Problem 26. A German silver alloy consistsof 60% copper, 25% zinc and 15% nickel.Determine the masses of the copper, zinc andnickel in a 3.74 kilogram block of the alloy

By direct proportion:

100% corresponds to 3.74 kg

1% corresponds to3.74

100D 0.0374 kg

60% corresponds to 60 0.0374 D 2.244 kg25% corresponds to 25 0.0374 D 0.935 kg15% corresponds to 15 0.0374 D 0.561 kg

Thus, the masses of the copper, zinc and nickel are2.244 kg, 0.935 kg and 0.561 kg, respectively.

(Check: 2.244 C 0.935 C 0.561 D 3.74)


Exercise 4 Further problems percentages

1. Convert to percentages:

(a) 0.057 (b) 0.374 (c) 1.285[(a) 5.7% (b) 37.4% (c) 128.5%]

2. Express as percentages, correct to 3significant figures:

(a)7

33(b)

19

24(c) 1

11

16

[(a) 21.2% (b) 79.2% (c) 169%]

3. Calculate correct to 4 significant figures:

(a) 18% of 2758 tonnes (b) 47% of

18.42 grams (c) 147% of 14.1 seconds

[(a) 496.4 t (b) 8.657 g (c) 20.73 s]

4. When 1600 bolts are manufactured, 36are unsatisfactory. Determine the percent-age unsatisfactory. [2.25%]

5. Express: (a) 140 kg as a percentage of1 t (b) 47 s as a percentage of 5 min(c) 13.4 cm as a percentage of 2.5 m

[(a) 14% (b) 15.67% (c) 5.36%]

6. A block of monel alloy consists of 70%nickel and 30% copper. If it contains88.2 g of nickel, determine the mass ofcopper in the block. [37.8 g]

7. A drilling machine should be set to250 rev/min. The nearest speed availableon the machine is 268 rev/min. Calculatethe percentage over speed. [7.2%]

8. Two kilograms of a compound contains30% of element A, 45% of element B and25% of element C. Determine the massesof the three elements present.

[A 0.6 kg, B 0.9 kg, C 0.5 kg]

9. A concrete mixture contains seven partsby volume of ballast, four parts by vol-ume of sand and two parts by volume ofcement. Determine the percentage of eachof these three constituents correct to thenearest 1% and the mass of cement in atwo tonne dry mix, correct to 1 significantfigure.

[54%, 31%, 15%, 0.3 t]

2

Indices and standard form

2.1 Indices

The lowest factors of 2000 are 2222555.These factors are written as 24 53, where 2 and 5are called bases and the numbers 4 and 3 are calledindices.

When an index is an integer it is called a power.Thus, 24 is called two to the power of four, andhas a base of 2 and an index of 4. Similarly, 53 iscalled five to the power of 3 and has a base of 5and an index of 3.

Special names may be used when the indices are2 and 3, these being called squared and cubed,respectively. Thus 72 is called seven squared and93 is called nine cubed. When no index is shown,the power is 1, i.e. 2 means 21.

Reciprocal

The reciprocal of a number is when the index is1 and its value is given by 1, divided by the base.Thus the reciprocal of 2 is 21 and its value is 12or 0.5. Similarly, the reciprocal of 5 is 51 whichmeans 15 or 0.2

Square root

The square root of a number is when the index is 12 ,and the square root of 2 is written as 21/2 or

p2. The

value of a square root is the value of the base whichwhen multiplied by itself gives the number. Since33 D 9, then p9 D 3. However, 33 D 9,so

p9 D 3. There are always two answers when

finding the square root of a number and this is shownby putting both a C and a sign in front of theanswer to a square root problem. Thus

p9 D 3

and 41/2 D p4 D 2, and so on.

Laws of indices

When simplifying calculations involving indices,certain basic rules or laws can be applied, calledthe laws of indices. These are given below.

(i) When multiplying two or more numbers hav-ing the same base, the indices are added. Thus

32 34 D 32C4 D 36

(ii) When a number is divided by a number havingthe same base, the indices are subtracted. Thus

35

32D 352 D 33

(iii) When a number which is raised to a poweris raised to a further power, the indices aremultiplied. Thus

352 D 352 D 310

(iv) When a number has an index of 0, its valueis 1. Thus 30 D 1

(v) A number raised to a negative power is thereciprocal of that number raised to a positive

power. Thus 34 D 134

Similarly,1

23D 23

(vi) When a number is raised to a fractional powerthe denominator of the fraction is the root ofthe number and the numerator is the power.

Thus 82/3 D 3p

82 D 22 D 4and 251/2 D 2

p251 D

p251 D 5

(Note thatp 2p )

2.2 Worked problems on indices

Problem 1. Evaluate: (a) 52 53,(b) 32 34 3 and (c) 2 22 25

From law (i):

(a) 5253 D 52C3 D 55 D 55555 D 3125


(b) 32 34 3 D 32C4C1 D 37D 3 3 to 7 termsD 2187

(c) 2 22 25 D 21C2C5 D 28 D 256

Problem 2. Find the value of:

(a)75

73and (b)

57

54

From law (ii):

(a)75

73D 753 D 72 D 49

(b)57

54D 574 D 53 D 125

Problem 3. Evaluate: (a) 52 53 54 and(b) 3 35 32 33

From laws (i) and (ii):

(a) 52 53 54 D 52 53

54D 5

2C3

54

D 55

54D 554 D 51 D 5

(b) 3 35 32 33 D 3 35

32 33 D31C5

32C3

D 36

35D 365 D 31 D 3

Problem 4. Simplify: (a) 234 (b) 325,

expressing the answers in index form.

From law (iii):

(a) 234 D 234 D 212 (b) 325 D 325 D 310

Problem 5. Evaluate:1023

104 102

From the laws of indices:1023

104 102 D1023

104C2D 10

6

106

D 1066 D 100 D 1

Problem 6. Find the value of

(a)23 2427 25 and (b)

323

3 39

From the laws of indices:

(a)23 2427 25 D

23C4

27C5D 2

7

212D 2712 D 25

D 125

D 132

(b)323

3 39 D323

31C9D 3

6

310D 3610 D 34

D 134

D 181


Exercise 5 Further problems on indices

In Problems 1 to 10, simplify the expressionsgiven, expressing the answers in index formand with positive indices:

1. (a) 33 34 (b) 42 43 44[(a) 37 (b) 49]

2. (a) 23 2 22 (b) 72 74 7 73[(a) 26 (b) 710]

3. (a)24

23(b)

37

32[(a) 2 (b) 35]

4. (a) 56 53 (b) 713/710[(a) 53 (b) 73]

5. (a) 723 (b) 332 [(a) 76 (b) 36]

6. (a)22 23

24(b)

37 3435

[(a) 2 (b) 36]

7. (a)57

52 53 (b)135

13 132[(a) 52 (b) 132]

8. (a)9 3233 272 (b)

16 422 83

[(a) 34 (b) 1]

INDICES AND STANDARD FORM 11

9. (a)52

54(b)

32 3433 [

(a) 52 (b)1

35

]

10. (a)72 737 74 (b)

23 24 252 22 26[

(a) 72 (b)1

2

]

2.3 Further worked problems onindices

Problem 7. Evaluate:33 5753 34

The laws of indices only apply to terms having thesame base. Grouping terms having the same base,and then applying the laws of indices to each of thegroups independently gives:

33 5753 34 D

33

34 5

7

53D 334 573

D 31 54 D 54

31D 625

3D 2081

3


23 35 72274 24 33

23 35 72274 24 33 D 2

34 353 7224

D 21 32 70

D 12

32 1 D 92

D 412

Problem 9. Evaluate:

(a) 41/2 (b) 163/4 (c) 272/3 (d) 91/2

(a) 41/2 D p4 D 2(b) 163/4 D 4

p163 D 23 D 8

(Note that it does not matter whether the 4th rootof 16 is found first or whether 16 cubed is foundfirst the same answer will result).

(c) 272/3 D 3p

272 D 32 D 9

(d) 91/2 D 191/2

D 1p9

D 13 D 13

Problem 10. Evaluate:41.5 81/3

22 322/5

41.5 D 43/2 Dp

43 D 23 D 8,81/3 D 3

p8 D 2, 22 D 4

and 322/5 D 1322/5

D 15

p322

D 122

D 14

Hence41.5 81/3

22 322/5 D8 24 1

4

D 161

D 16

Alternatively,

41.5 81/322 322/5 D

[22]3/2 231/322 252/5 D

23 2122 22

D 23C122 D 24 D 16

Problem 11. Evaluate:32 55 C 33 53

34 54

Dividing each term by the HCF (i.e. highest com-mon factor) of the three terms, i.e. 32 53, gives:

32 55 C 33 5334 54 D

32 5532 53 C

33 5332 53

34 5432 53

D 322 553 C 332 50

342 543

D 30 52 C 31 50

32 51

D 1 25 C 3 19 5 D

2845


32 5534 54 C 33 53


To simplify the arithmetic, each term is divided bythe HCF of all the terms, i.e. 32 53. Thus

32 5534 54 C 33 53

D32 5532 53

34 5432 53 C

33 5332 53

D 322 553

342 543 C 332 533

D 30 52

32 51 C 31 50 D25

45 C 3 D2548

Problem 13. Simplify:

(4

3

)3(

3

5

)2(

2

5

)3giving the answer with positive indices

A fraction raised to a power means that both thenumerator and the denominator of the fraction are

raised to that power, i.e.(

4

3

)3D 4

3

33

A fraction raised to a negative power has thesame value as the inverse of the fraction raised to apositive power.

Thus,(

3

5

)2D 1(

3

5

)2 D 13252

D 1 52

32D 5

2

32

Similarly,(

2

5

)3D(

5

2

)3D 5

3

23

Thus,

(4

3

)3(

3

5

)2(

2

5

)3 D43

33 5

2

32

53

23

D 43

33 5

2

32 2

3

53

D 223 23

33C2 532

D 29

35 5


Exercise 6 Further problems on indices

In Problems 1 and 2, simplify the expressionsgiven, expressing the answers in index formand with positive indices:

1. (a)33 5254 34 (b)

72 3235 74 73[

(a)1

3 52 (b)1

73 37]

2. (a)42 9383 34 (b)

82 52 34252 24 92[(a)

32

25(b)

1

210 52]

3. Evaluate a(

1

32

)1b 810.25

c 161/4 d(

4

9

)1/2

[(a) 9 (b) 3 (c) 1

2(d) 2

3

]

In Problems 4 to 8, evaluate the expressionsgiven.

4.92 74

34 74 C 33 72[

147

148

]

5.242 32 44

23 162[

1

9

]

6.

(1

2

)3(

2

3

)2(

3

5

)2[565

72

]

7.

(4

3

)4(

2

9

)2 [64]

8.323/2 81/32

32 431/2 91/2[

41

2

]


2.4 Standard form

A number written with one digit to the left of thedecimal point and multiplied by 10 raised to somepower is said to be written in standard form. Thus:5837 is written as 5.837 103 in standard form,and 0.0415 is written as 4.15 102 in standardform.

When a number is written in standard form, thefirst factor is called the mantissa and the secondfactor is called the exponent. Thus the number5.8 103 has a mantissa of 5.8 and an exponentof 103.

(i) Numbers having the same exponent can beadded or subtracted in standard form by addingor subtracting the mantissae and keeping theexponent the same. Thus:

2.3 104 C 3.7 104D 2.3 C 3.7 104 D 6.0 104

and 5.9 102 4.6 102D 5.9 4.6 102 D 1.3 102

When the numbers have different exponents,one way of adding or subtracting the numbersis to express one of the numbers in non-standard form, so that both numbers have thesame exponent. Thus:

2.3 104 C 3.7 103D 2.3 104 C 0.37 104D 2.3 C 0.37 104 D 2.67 104

Alternatively,

2.3 104 C 3.7 103D 23 000 C 3700 D 26 700D 2.67 104

(ii) The laws of indices are used when multiplyingor dividing numbers given in standard form.For example,

2.5 103 5 102D 2.5 5 103C2D 12.5 105 or 1.25 106

Similarly,

6 1041.5 102 D

6

1.5 1042 D 4 102

2.5 Worked problems on standardform

Problem 14. Express in standard form:(a) 38.71 (b) 3746 (c) 0.0124

For a number to be in standard form, it is expressedwith only one digit to the left of the decimal point.Thus:

(a) 38.71 must be divided by 10 to achieve onedigit to the left of the decimal point and itmust also be multiplied by 10 to maintain theequality, i.e.

38.71 D 38.7110

10 D 3.871 10 in standardform

(b) 3746 D 37461000

1000 D 3.746 103 in stan-dard form

(c) 0.0124 D 0.0124 100100

D 1.24100

D 1.24 102 in standard form

Problem 15. Express the followingnumbers, which are in standard form, asdecimal numbers: (a) 1.725 102(b) 5.491 104 (c) 9.84 100

(a) 1.725 102 D 1.725100

D 0.01725(b) 5.491 104 D 5.491 10 000 D 54 910(c) 9.84 100 D 9.84 1 D 9.84 (since 100 D 1)

Problem 16. Express in standard form,correct to 3 significant figures:

(a)3

8(b) 19

2

3(c) 741

9

16


(a)3

8D 0.375, and expressing it in standard form

gives: 0.375 D 3.75 101

(b) 192

3D 19.P6 D 1.97 10 in standard form,

correct to 3 significant figures

(c) 7419

16D 741.5625 D 7.42 102 in standard

form, correct to 3 significant figures

Problem 17. Express the followingnumbers, given in standard form, as fractionsor mixed numbers: (a) 2.5 101(b) 6.25 102 (c) 1.354 102

(a) 2.5 101 D 2.510

D 25100

D 14

(b) 6.25 102 D 6.25100

D 62510 000

D 116

(c) 1.354 102 D 135.4 D 135 410

D 13525


Exercise 7 Further problems on standardform

In Problems 1 to 4, express in standard form:

1. (a) 73.9 (b) 28.4 (c) 197.72[ (a) 7.39 10 (b) 2.84 10(c) 1.9762 102

]

2. (a) 2748 (b) 33170 (c) 274218[ (a) 2.748 103 (b) 3.317 104(c) 2.74218 105

]

3. (a) 0.2401 (b) 0.0174 (c) 0.00923[(a) 2.401 101 (b) 1.74 102(c) 9.23 103

]

4. (a)1

2(b) 11

7

8(c) 130

3

5(d)

1

32[(a) 5 101 (b) 1.1875 10(c) 1.306 102 (d) 3.125 102

]

In Problems 5 and 6, express the numbersgiven as integers or decimal fractions:

5. (a) 1.01 103 (b) 9.327 102(c) 5.41 104 (d) 7 100[(a) 1010 (b) 932.7 (c) 54 100 (d) 7]

6. (a) 3.89 102 (b) 6.741 101(c) 8 103

[(a) 0.0389 (b) 0.6741 (c) 0.008]

2.6 Further worked problems onstandard form

Problem 18. Find the value of:

(a) 7.9 102 5.4 102(b) 8.3 103 C 5.415 103 and(c) 9.293 102 C 1.3 103 expressing the

answers in standard form.

Numbers having the same exponent can be addedor subtracted by adding or subtracting the mantissaeand keeping the exponent the same. Thus:

(a) 7.9 102 5.4 102D 7.9 5.4 102 D 2.5 102

(b) 8.3 103 C 5.415 103D 8.3 C 5.415 103 D 13.715 103D 1.3715 104 in standard form

(c) Since only numbers having the same exponentscan be added by straight addition of the man-tissae, the numbers are converted to this formbefore adding. Thus:

9.293 102 C 1.3 103D 9.293 102 C 13 102D 9.293 C 13 102D 22.293 102 D 2.2293 103

in standard form.

Alternatively, the numbers can be expressed asdecimal fractions, giving:

9.293 102 C 1.3 103D 929.3 C 1300 D 2229.3D 2.2293 103

in standard form as obtained previously. Thismethod is often the safest way of doing thistype of problem.


Problem 19. Evaluate

(a) 3.75 1036 104 and (b) 3.5 105

7 102expressing answers in standard form

(a) 3.75 1036 104 D 3.75 6103C4D 22.50 107D 2.25 108

(b)3.5 1057 102 D

3.5

7 1052

D 0.5 103 D 5 102


Exercise 8 Further problems on standardform

In Problems 1 to 4, find values of the expres-sions given, stating the answers in standardform:

1. (a) 3.7 102 C 9.81 102(b) 1.431 101 C 7.3 101

[(a) 1.351 103 (b) 8.731 101]2. (a) 4.831 102 C 1.24 103

(b) 3.24 103 1.11 104[(a) 1.7231 103 (b) 3.129 103]

3. (a) 4.5 1023 103(b) 2 5.5 104

[(a) 1.35 102 (b) 1.1 105]

4. (a)6 1033 105 (b)

2.4 1033 1024.8 104

[(a) 2 102 (b) 1.5 103]5. Write the following statements in stan-

dard form:

(a) The density of aluminium is2710 kg m3

[2.71 103 kg m3](b) Poissons ratio for gold is 0.44

[4.4 101](c) The impedance of free space is

376.73 [3.7673 102 ](d) The electron rest energy is

0.511 MeV [5.11 101 MeV](e) Proton charge-mass ratio is

9 5 789 700 C kg1

[9.57897 107 C kg1](f) The normal volume of a perfect gas

is 0.02241 m3 mol1

[2.241 102 m3 mol1]

3

Computer numbering systems

3.1 Binary numbers

The system of numbers in everyday use is thedenary or decimal system of numbers, usingthe digits 0 to 9. It has ten different digits(0, 1, 2, 3, 4, 5, 6, 7, 8 and 9) and is said to have aradix or base of 10.

The binary system of numbers has a radix of 2and uses only the digits 0 and 1.

3.2 Conversion of binary to decimal

The decimal number 234.5 is equivalent to

2 102 C 3 101 C 4 100 C 5 101

i.e. is the sum of terms comprising: (a digit) multi-plied by (the base raised to some power).

In the binary system of numbers, the base is 2, so1101.1 is equivalent to:

1 23 C 1 22 C 0 21 C 1 20 C 1 21

Thus the decimal number equivalent to the binarynumber 1101.1 is

8 C 4 C 0 C 1 C 12, that is 13.5

i.e. 1101.12 = 13.510, the suffixes 2 and 10 denot-ing binary and decimal systems of numbers respec-tively.

Problem 1. Convert 110112 to a decimalnumber

From above: 110112 D 1 24 C 1 23 C 0 22C 1 21 C 1 20

D 16 C 8 C 0 C 2 C 1D 2710

Problem 2. Convert 0.10112 to a decimalfraction

0.10112 D 1 21 C 0 22 C 1 23C 1 24

D 1 12

C 0 122

C 1 123

C 1 124

D 12

C 18

C 116

D 0.5 C 0.125 C 0.0625D 0.687510

Problem 3. Convert 101.01012 to a decimalnumber

101.01012 D 1 22 C 0 21 C 1 20C 0 21 C 1 22C 0 23 C 1 24

D 4 C 0 C 1 C 0 C 0.25C 0 C 0.0625

D 5.312510


Exercise 9 Further problems on conver-sion of binary to decimal num-bers

In Problems 1 to 4, convert the binary num-bers given to decimal numbers.

1. (a) 110 (b) 1011 (c) 1110 (d) 1001

[(a) 610 (b) 1110 (c) 1410 (d) 910]

COMPUTER NUMBERING SYSTEMS 17

2. (a) 10101 (b) 11001 (c) 101101

(d) 110011

[(a) 2110 (b) 2510 (c) 4510 (d) 5110]

3. (a) 0.1101 (b) 0.11001 (c) 0.00111

(d) 0.01011[(a) 0.812510 (b) 0.7812510(c) 0.2187510 (d) 0.3437510

]

4. (a) 11010.11 (b) 10111.011

(c) 110101.0111 (d) 11010101.10111[(a) 26.7510 (b) 23.37510

(c) 53.437510 (d) 213.7187510

]

3.3 Conversion of decimal to binary

An integer decimal number can be converted to acorresponding binary number by repeatedly dividingby 2 and noting the remainder at each stage, asshown below for 3910

0 1

1 0 0 1 1 1

2 39 Remainder2 19 12 9 12 4 12 2 02 1 0

(most significant bit)

(least significant bit)

The result is obtained by writing the top digit ofthe remainder as the least significant bit, (a bit is abinary digit and the least significant bit is the oneon the right). The bottom bit of the remainder is themost significant bit, i.e. the bit on the left.

Thus 3910 = 1001112

The fractional part of a decimal number can be con-verted to a binary number by repeatedly multiplyingby 2, as shown below for the fraction 0.625

0.625 2 = 1. 250

0.250 2 = 0. 500

0.500 2 = 1. 000

11 0.(most significant bit) (least significant bit)

For fractions, the most significant bit of the resultis the top bit obtained from the integer part ofmultiplication by 2. The least significant bit of theresult is the bottom bit obtained from the integerpart of multiplication by 2.

Thus 0.62510 = 0.1012

Problem 4. Convert 4710 to a binarynumber

From above, repeatedly dividing by 2 and noting theremainder gives:

2 47 Remainder

2 23 1

2 11 1

2 5 1

2 2 1

2 1 0

0 1

1 0 1 1 1 1

Thus 4710 = 1011112

Problem 5. Convert 0.4062510 to a binarynumber

From above, repeatedly multiplying by 2 gives:

0.40625 2 = 0. 8125

0.8125 2 = 1. 625

0.625 2 = 1. 25

0.25 2 = 0. 5

0.5 2 = 1. 0

. 0 1 1 0 1

i.e. 0.4062510 = 0.011012

Problem 6. Convert 58.312510 to a binarynumber


The integer part is repeatedly divided by 2, giving:

2 58 Remainder2 29 02 14 12 7 02 3 12 1 1

0 1

1 1 1 1 0 0

The fractional part is repeatedly multiplied by 2giving:

0.3125 2 = 0.6250.625 2 = 1.250.25 2 = 0.50.5 2 = 1.0

. 0 1 0 1

Thus 58.312510 = 111010.01012


Exercise 10 Further problems on conver-sion of decimal to binarynumbers

In Problems 1 to 4, convert the decimalnumbers given to binary numbers.

1. (a) 5 (b) 15 (c) 19 (d) 29[(a) 1012 (b) 11112(c) 100112 (d) 111012

]

2. (a) 31 (b) 42 (c) 57 (d) 63[(a) 111112 (b) 1010102(c) 1110012 (d) 1111112

]

3. (a) 0.25 (b) 0.21875 (c) 0.28125(d) 0.59375[

(a) 0.012 (b) 0.001112(c) 0.010012 (d) 0.100112

]

4. (a) 47.40625 (b) 30.8125(c) 53.90625 (d) 61.65625[

(a) 101111.011012 (b) 11110.11012(c) 110101.111012 (d) 111101.101012

]

3.4 Conversion of decimal to binaryvia octal

For decimal integers containing several digits, repe-atedly dividing by 2 can be a lengthy process. Inthis case, it is usually easier to convert a decimalnumber to a binary number via the octal system ofnumbers. This system has a radix of 8, using thedigits 0, 1, 2, 3, 4, 5, 6 and 7. The denary numberequivalent to the octal number 43178 is

4 83 C 3 82 C 1 81 C 7 80i.e. 4 512 C 3 64 C 1 8 C 7 1 or 225510An integer decimal number can be converted to acorresponding octal number by repeatedly dividingby 8 and noting the remainder at each stage, asshown below for 49310

8 493 Remainder

8 61 5

8 7 5

0 7

7 5 5

Thus 49310 = 7558The fractional part of a decimal number can be con-verted to an octal number by repeatedly multiplyingby 8, as shown below for the fraction 0.437510

0.4375 8 = 3 . 5

0.5 8 =

. 3 4

4 . 0

For fractions, the most significant bit is the topinteger obtained by multiplication of the decimalfraction by 8, thus

0.437510 D 0.348The natural binary code for digits 0 to 7 is shownin Table 3.1, and an octal number can be convertedto a binary number by writing down the three bitscorresponding to the octal digit.

Thus 4378 D 100 011 1112and 26.358 D 010 110.011 1012


Table 3.1

Octal digit Naturalbinary number

0 0001 0012 0103 0114 1005 1016 1107 111

The 0 on the extreme left does not signify any-thing, thus 26.358 D 10 110.011 1012Conversion of decimal to binary via octal is demon-strated in the following worked problems.

Problem 7. Convert 371410 to a binarynumber, via octal

Dividing repeatedly by 8, and noting the remaindergives:

8 58 0

0 7

7 2 0 2

8 3714 Remainder8 464 2

8 7 2

From Table 3.1, 72028 D 111 010 000 0102i.e. 371410 = 111 010 000 0102

Problem 8. Convert 0.5937510 to a binarynumber, via octal

Multiplying repeatedly by 8, and noting the integervalues, gives:

0.59375 8 = 4.750.75 8 = 6.00

. 4 6

Thus 0.5937510 D 0.468From Table 3.1, 0.468 D 0.100 1102i.e. 0.5937510 = 0.100 112

Problem 9. Convert 5613.9062510 to abinary number, via octal

The integer part is repeatedly divided by 8, notingthe remainder, giving:

8 5613 Remainder8 701 588

87 510

8 1 0

721

2 7 5 51

This octal number is converted to a binary number,(see Table 3.1)

127558 D 001 010 111 101 1012i.e. 561310 D 1 010 111 101 1012The fractional part is repeatedly multiplied by 8, andnoting the integer part, giving:

0.90625 8 = 7.250.25 8 = 2.00

. 7 2

This octal fraction is converted to a binary number,(see Table 3.1)

0.728 D 0.111 0102i.e. 0.9062510 D 0.111 012Thus, 5613.9062510 = 1 010 111 101 101.111 012

Problem 10. Convert 11 110 011.100 012to a decimal number via octal

Grouping the binary number in threes from thebinary point gives: 011 110 011.100 0102

Using Table 3.1 to convert this binary number toan octal number gives: 363.428 and

363.428 D 3 82 C 6 81 C 3 80C 4 81 C 2 82

D 192 C 48 C 3 C 0.5 C 0.03125D 243.5312510



Exercise 11 Further problems on con-version between decimal andbinary numbers via octal

In Problems 1 to 3, convert the decimalnumbers given to binary numbers, via octal.

1. (a) 343 (b) 572 (c) 1265[

(a) 1010101112 (b) 10001111002

(c) 100111100012

]

2. (a) 0.46875 (b) 0.6875 (c) 0.71875[

(a) 0.011112 (b) 0.10112

(c) 0.101112

]

3. (a) 247.09375 (b) 514.4375

(c) 1716.78125

(a) 11110111.000112(b) 1000000010.01112(c) 11010110100.110012

4. Convert the following binary numbers todecimal numbers via octal:

(a) 111.011 1 (b) 101 001.01(c) 1 110 011 011 010.001 1

[(a) 7.437510 (b) 41.2510

(c) 7386.187510

]

3.5 Hexadecimal numbers

The complexity of computers requires higher ordernumbering systems such as octal (base 8) and hex-adecimal (base 16), which are merely extensionsof the binary system. A hexadecimal numberingsystem has a radix of 16 and uses the following 16distinct digits:

0, 1, 2, 3, 4, 5, 6, 7, 8, 9,A,B,C,D,E and F

A corresponds to 10 in the denary system, B to11, C to 12, and so on.

To convert from hexadecimal to decimal:

For example

1A16 D 1 161 C A 160D 1 161 C 10 1 D 16 C 10 D 26

i.e. 1A16 D 2610Similarly,

2E16 D 2 161 C E 160D 2 161 C 14 160 D 32 C 14 D 4610

and 1BF16 D 1 162 C B 161 C F 160D 1 162 C 11 161 C 15 160D 256 C 176 C 15 D 44710

Table 3.2 compares decimal, binary, octal and hex-adecimal numbers and shows, for example, that

2310 D 101112 D 278 D 1716

Problem 11. Convert the followinghexadecimal numbers into their decimalequivalents: (a) 7A16 (b) 3F16

(a) 7A16 D 7 161 C A 160 D 7 16 C 10 1D 112 C 10 D 122

Thus 7A16 = 12210

(b) 3F16 D 3 161 C F 160 D 3 16 C 15 1D 48 C 15 D 63

Thus, 3F16 = 6310

Problem 12. Convert the followinghexadecimal numbers into their decimalequivalents: (a) C916 (b) BD16

(a) C916 D C 161 C 9 160 D 12 16 C 9 1D 192 C 9 D 201

Thus C916 = 20110

(b) BD16 D B 161 C D 160 D 11 16 C 13 1D 176 C 13 D 189

Thus BD16 = 18910

Problem 13. Convert 1A4E16 into a denarynumber


Table 3.2

Decimal Binary Octal Hexadecimal

0 0000 0 01 0001 1 12 0010 2 23 0011 3 34 0100 4 45 0101 5 56 0110 6 67 0111 7 78 1000 10 89 1001 11 9

10 1010 12 A11 1011 13 B12 1100 14 C13 1101 15 D14 1110 16 E15 1111 17 F16 10000 20 1017 10001 21 1118 10010 22 1219 10011 23 1320 10100 24 1421 10101 25 1522 10110 26 1623 10111 27 1724 11000 30 1825 11001 31 1926 11010 32 1A27 11011 33 1B28 11100 34 1C29 11101 35 1D30 11110 36 1E31 11111 37 1F32 100000 40 20

1A4E16D 1 163 C A 162 C 4 161 C E 160D 1 163 C 10 162 C 4 161 C 14 160D 1 4096 C 10 256 C 4 16 C 14 1D 4096 C 2560 C 64 C 14 D 6734

Thus, 1A4E16 = 673410

To convert from decimal to hexadecimal:

This is achieved by repeatedly dividing by 16 andnoting the remainder at each stage, as shown belowfor 2610

0 1 116

most significant bit 1 A least significant bit

16 A1610116 Remainder26

Hence 2610 = 1A16

Similarly, for 44710

1616 11 B16

0 1 1161 B F

16

15 F16

Remainder447

271

Thus 44710 = 1BF16

Problem 14. Convert the following decimalnumbers into their hexadecimal equivalents:(a) 3710 (b) 10810

(a) 1616 = 516

0 2 = 216most significant bit 2 5 least significant bit

Remainder5

372

Hence 3710 = 2516(b) 16

16 = C160 = 616

C

Remainder126

6108

6

Hence 10810 = 6C16

Problem 15. Convert the following decimalnumbers into their hexadecimal equivalents:(a) 16210 (b) 23910

(a) 1616 = 216

0 = A16A

Remainder2

10 10

162

2

Hence 16210 = A216(b) 16

16 = F160 = E16

E

Remainder1514

14239

F

Hence 23910 = EF16

To convert from binary to hexadecimal:

The binary bits are arranged in groups of four,starting from right to left, and a hexadecimal symbol


is assigned to each group. For example, the binarynumber 1110011110101001 is initially grouped in

fours as: 1110 0111 1010 1001

and a hexadecimal symbol

assigned to each group as E 7 A 9from Table 3.2

Hence 11100111101010012 = E7A916.

To convert from hexadecimal to binary:

The above procedure is reversed, thus, for example,

6CF316 D 0110 1100 1111 0011from Table 3.2

i.e. 6CF316= 1101100111100112

Problem 16. Convert the following binarynumbers into their hexadecimal equivalents:(a) 110101102 (b) 11001112

(a) Grouping bits in fours from the

right gives: 1101 0110

and assigning hexadecimal symbols

to each group gives: D 6from Table 3.2

Thus, 110101102 = D616(b) Grouping bits in fours from the


and assigning hexadecimal symbols

to each group gives: 6 7from Table 3.2

Thus, 11001112 = 6716

Problem 17. Convert the following binarynumbers into their hexadecimal equivalents:(a) 110011112 (b) 1100111102

(a) Grouping bits in fours from the


and assigning hexadecimal

symbols to each group gives: C Ffrom Table 3.2

Thus, 110011112 = CF16

(b) Grouping bits in fours from

the right gives: 0001 1001 1110

and assigning hexadecimal

symbols to each group gives: 1 9 Efrom Table 3.2

Thus, 1100111102 = 19E16

Problem 18. Convert the followinghexadecimal numbers into their binaryequivalents: (a) 3F16 (b) A616

(a) Spacing out hexadecimal

digits gives: 3 F

and converting each into

binary gives: 0011 1111from Table 3.2

Thus, 3F16 = 1111112(b) Spacing out hexadecimal digits

gives: A 6

and converting each into binary

gives: 1010 0110from Table 3.2

Thus, A616 = 101001102

Problem 19. Convert the followinghexadecimal numbers into their binaryequivalents: (a) 7B16 (b) 17D16

(a) Spacing out hexadecimal

digits gives: 7 B


binary gives: 0111 1011from Table 3.2

Thus, 7B16 = 11110112

(b) Spacing out hexadecimal

digits gives: 1 7 D


binary gives: 0001 0111 1101from Table 3.2

Thus, 17D16 = 1011111012



Exercise 12 Further problems on hexa-decimal numbers

In Problems 1 to 4, convert the given hexadec-imal numbers into their decimal equivalents.

1. E716 [23110] 2. 2C16 [4410]

3. 9816 [15210] 4. 2F116 [75310]

In Problems 5 to 8, convert the given decimalnumbers into their hexadecimal equivalents.

5. 5410 [3616] 6. 20010 [C816]

7. 9110 [5B16] 8. 23810 [EE16]

In Problems 9 to 12, convert the given binarynumbers into their hexadecimal equivalents.

9. 110101112 [D716]

10. 111010102 [EA16]

11. 100010112 [8B16]

12. 101001012 [A516]

In Problems 13 to 16, convert the given hex-adecimal numbers into their binary equiva-lents.

13. 3716 [1101112]

14. ED16 [111011012]

15. 9F16 [100111112]

16. A2116 [1010001000012]

4

Calculations and evaluation offormulae

4.1 Errors and approximations

(i) In all problems in which the measurement ofdistance, time, mass or other quantities occurs,an exact answer cannot be given; only ananswer which is correct to a stated degree ofaccuracy can be given. To take account of thisan error due to measurement is said to exist.

(ii) To take account of measurement errors itis usual to limit answers so that the resultgiven is not more than one significant figuregreater than the least accurate numbergiven in the data.

(iii) Rounding-off errors can exist with decimalfractions. For example, to state that D3.142 is not strictly correct, but D 3.142correct to 4 significant figures is a true state-ment. (Actually, D 3.14159265 . . .)

(iv) It is possible, through an incorrect procedure,to obtain the wrong answer to a calculation.This type of error is known as a blunder.

(v) An order of magnitude error is said to existif incorrect positioning of the decimal pointoccurs after a calculation has been completed.

(vi) Blunders and order of magnitude errors canbe reduced by determining approximate val-ues of calculations. Answers which do notseem feasible must be checked and the cal-culation must be repeated as necessary.

An engineer will often need to make aquick mental approximation for a calcula-

tion. For example,49.1 18.4 122.1

61.2 38.1 may

be approximated to50 20 120

60 40 and then,

by cancelling,50 1 20 120 2 1

1 60 40 2 1D 50. An

accurate answer somewhere between 45 and

55 could therefore be expected. Certainlyan answer around 500 or 5 would not beexpected. Actually, by calculator

49.1 18.4 122.161.2 38.1 D 47.31, correct to

4 significant figures.

Problem 1. The area A of a triangle is

given by A D 12bh. The base b when

measured is found to be 3.26 cm, and theperpendicular height h is 7.5 cm. Determinethe area of the triangle.

Area of triangle D 12bh D 1

2 3.26 7.5 D

12.225 cm2 (by calculator).

The approximate value is1

238 D 12 cm2, so

there are no obvious blunder or magnitude errors.However, it is not usual in a measurement typeproblem to state the answer to an accuracy greaterthan 1 significant figure more than the least accuratenumber in the data: this is 7.5 cm, so the resultshould not have more than 3 significant figures

Thus, area of triangle = 12.2 cm2

Problem 2. State which type of error hasbeen made in the following statements:

(a) 72 31.429 D 2262.9(b) 16 0.08 7 D 89.6(c) 11.714 0.0088 D 0.3247 correct to

4 decimal places.

(d)29.74 0.0512

11.89D 0.12, correct to

2 significant figures.

CALCULATIONS AND EVALUATION OF FORMULAE 25

(a) 72 31.429 D 2262.888 (by calculator),hence a rounding-off error has occurred. Theanswer should have stated:

72 31.429 D 2262.9, correct to 5 significantfigures or 2262.9, correct to 1 decimal place.

(b) 16 0.08 7 D 16 8100

7 D 32 725

D 22425

D 82425

D 8.96

Hence an order of magnitude error hasoccurred.

(c) 11.714 0.0088 is approximately equal to12 9 103, i.e. about 108 103 or 0.108.Thus a blunder has been made.

(d) 29.74 0.051211.89

30 5 102

12

D 15012 102 D

15

120D 1

8or 0.125

hence no order of magnitude error has

occurred. However,29.74 0.0512

11.89D 0.128

correct to 3 significant figures, which equals0.13 correct to 2 significant figures.

Hence a rounding-off error has occurred.

Problem 3. Without using a calculator,determine an approximate value of:

(a)11.7 19.19.3 5.7 (b)

2.19 203.6 17.9112.1 8.76

(a)11.7 19.19.3 5.7 is approximately equal to

10 2010 5 , i.e. about 4

(By calculator,11.7 19.19.3 5.7 D 4.22, correct to

3 significant figures.)

(b)2.19 203.6 17.91

12.1 8.76 2 20 200 20 2

1 10 10 1D 2 20 2 after cancelling,

i.e.2.19 203.6 17.91

12.1 8.76 80

(By calculator,2.19 203.6 17.91

12.1 8.76 D 75.3,

correct to 3 significant figures.)


Exercise 13 Further problems on errors

In Problems 1 to 5 state which type of error,or errors, have been made:

1. 25 0.06 1.4 D 0.21[order of magnitude error]

2. 137 6.842 D 937.4[Rounding-off errorshould add correctto 4 significant figures or correct to1 decimal place

]

3.24 0.008

12.6D 10.42 [Blunder]

4. For a gas pV D c. When pressurep D 1 03 400 Pa and V D 0.54 m3 thenc D 55 836 Pa m3.[Measured values, hence

c D 55 800 Pa m3]

5.4.6 0.07

52.3 0.274 D 0.225

Order of magnitude error and rounding-off errorshould be 0.0225, correct to3 significant figures or 0.0225,correct to 4 decimal places

In Problems 6 to 8, evaluate the expressionsapproximately, without using a calculator.

6. 4.7 6.3 [30 (29.61, by calculator)]

7.2.87 4.076.12 0.96[2 (1.988, correct to 4 s.f., by

calculator)

]

8.72.1 1.96 48.6

139.3 5.2[10 (9.481, correct to 4 s.f., bycalculator)

]


4.2 Use of calculator

The most modern aid to calculations is the pocket-sized electronic calculator. With one of these, cal-culations can be quickly and accurately performed,correct to about 9 significant figures. The scientifictype of calculator has made the use of tables andlogarithms largely redundant.

To help you to become competent at using yourcalculator check that you agree with the answers tothe following problems:

Problem 4. Evaluate the following, correctto 4 significant figures:

(a) 4.7826 C 0.02713 (b) 17.6941 11.8762(c) 21.93 0.012981

(a) 4.7826 C 0.02713 D 4.80973 D 4.810, correctto 4 significant figures

(b) 17.6941 11.8762 D 5.8179 D 5.818, correctto 4 significant figures

(c) 21.93 0.012981 D 0.2846733 . . . D 0.2847,correct to 4 significant figures

Problem 5. Evaluate the following, correctto 4 decimal places:

(a) 46.32 97.17 0.01258 (b) 4.62123.76

(c)1

262.49 0.0172

(a) 46.32 97.17 0.01258 D 56.6215031 . . . D56.6215, correct to 4 decimal places

(b)4.621

23.76D 0.19448653 . . . D 0.1945, correct to

4 decimal places

(c)1

262.49 0.0172 D 0.537414 D 0.5374,

correct to 4 decimal places


(a)1

52.73(b)

1

0.0275(c)

1

4.92C 1

1.97

(a)1

52.73D 0.01896453 . . . D 0.019, correct to 3

decimal places

(b)1

0.0275D 36.3636363 . . . D 36.364, correct to

3 decimal places

(c)1

4.92C 1

1.97D 0.71086624 . . . D 0.711, cor-

rect to 3 decimal places

Problem 7. Evaluate the following,expressing the answers in standard form,correct to 4 significant figures.

(a) 0.004512 (b) 631.7 6.21 C 2.952

(c) 46.272 31.792

(a) 0.004512 D 2.03401105 D 2.034 105,correct to 4 significant figures

(b) 631.7 6.21 C 2.952 D 547.7944 D5.477944 102 D 5.478 102, correct to 4significant figures

(c) 46.272 31.792 D 1130.3088 D 1.130 103,correct to 4 significant figures


(a)2.372

0.0526(b)(

3.60

1.92

)2C(

5.40

2.45

)2

(c)15

7.62 4.82

(a)2.372

0.0526D 106.785171 . . . D 106.785, correct

to 3 decimal places

(b)(

3.60

1.92

)2C(

5.40

2.45

)2D 8.37360084 . . . D

8.374, correct to 3 decimal places

(c)15

7.62 4.82 D 0.43202764 . . . D 0.432, cor-

rect to 3 decimal places



(a)p

5.462 (b)p

54.62 (c)p

546.2

(a)p

5.462 D 2.3370922 . . . D 2.337, correct to 4significant figures

(b)p

54.62 D 7.39053448 . . . D 7.391, correct to4 significant figures

(c)p

546.2 D 23.370922 . . . D 23.37, correct to 4significant figures


(a)p

0.007328 (b)p

52.91 p31.76(c)

p1.6291 104

(a)p

0.007328 D 0.08560373 D 0.086, correct to3 decimal places

(b)p

52.91 p31.76 D 1.63832491 . . . D 1.638,correct to 3 decimal places

(c)p

1.6291 104 D p16291 D 127.636201. . . D 127.636, correct to 3 decimal places


(a) 4.723 (b) 0.83164

(c)p

76.212 29.102

(a) 4.723 D 105.15404 . . . D 105.2, correct to 4significant figures

(b) 0.83164 D 0.47825324 . . . D 0.4783, correctto 4 significant figures

(c)p

76.212 29.102 D 70.4354605 . . . D 70.44,correct to 4 significant figures


(a)

6.092

25.2 p7 (b)3

p47.291

(c)p

7.2132 C 6.4183 C 3.2914

(a)

6.092

25.2 p7 D 0.74583457 . . . D 0.746, cor-rect to 3 significant figures

(b) 3p

47.291 D 3.61625876 . . . D 3.62, correct to3 significant figures

(c)p

7.2132 C 6.4183 C 3.2914 D 20.8252991. . . D 20.8, correct to 3 significant figures

Problem 13. Evaluate the following,expressing the answers in standard form,correct to 4 decimal places:

(a) 5.176 1032

(b)(

1.974 101 8.61 1023.462

)4

(c)p

1.792 104

(a) 5.176 1032 D 2.679097 . . . 105 D2.6791 105, correct to 4 decimal places

(b)(

1.974 101 8.61 1023.462

)4

D 0.05808887 . . .D 5.8089 102,

correct to 4 decimal places

(c)p

1.792 104 D 0.0133865 . . .D 1.3387 102, correct to 4 decimal places


Exercise 14 Further problems on use ofcalculator

In Problems 1 to 9, use a calculator to evaluatethe quantities shown correct to 4 significantfigures:

1. (a) 3.2492 (b) 73.782 (c) 311.42

(d) 0.06392[(a) 10.56 (b) 5443 (c) 96 970

(d) 0.004083

]

2. (a)p

4.735 (b)p

35.46 (c)p

73 280(d)

p0.0256[ (a) 2.176 (b) 5.955 (c) 270.7(d) 0.1600

]


3. (a)1

7.768(b)

1

48.46(c)

1

0.0816

(d)1

1.118 [(a) 0.1287 (b) 0.02064(c) 12.25 (d) 0.8945

]

4. (a) 127.8 0.0431 19.8(b) 15.76 4.329

[(a) 109.1 (b) 3.641]

5. (a)137.6

552.9(b)

11.82 1.7360.041

[(a) 0.2489 (b) 500.5]

6. (a) 13.63 (b) 3.4764 (c) 0.1245

[(a) 2515 (b) 146.0 (c) 0.00002932]

7. (a)(

24.68 0.05327.412

)3

(b)(

0.2681 41.2232.6 11.89

)4

[(a) 0.005559 (b) 1.900]

8. (a)14.323

21.682(b)

4.8213

17.332 15.86 11.6[(a) 6.248 (b) 0.9630]

9. (a)

15.622

29.21 p10.52(b)

p6.9212 C 4.8163 2.1614

[(a) 1.605 (b) 11.74]

10. Evaluate the following, expressing theanswers in standard form, correct to3 decimal places: (a) 8.291 1022(b)

p7.623 103

[(a) 6.874 103 (b) 8.731 102]

4.3 Conversion tables and charts

It is often necessary to make calculations from vari-ous conversion tables and charts. Examples includecurrency exchange rates, imperial to metric unitconversions, train or bus timetables, productionschedules and so on.

Problem 14. Currency exchange rates forfive countries are shown in Table 4.1

Table 4.1

France 1 D 1.46 eurosJapan 1 D 190 yenNorway 1 D 10.90 kronorSwitzerland 1 D 2.15 francsU.S.A. 1 D 1.52 dollars ($)

Calculate:

(a) how many French euros 27.80 will buy

(b) the number of Japanese yen which canbe bought for 23

(c) the pounds sterling which can beexchanged for 6409.20Norwegian kronor

(d) the number of American dollars whichcan be purchased for 90, and

(e) the pounds sterling which can beexchanged for 2795 Swiss francs

(a) 1 D 1.46 euros, hence27.80 D 27.80 1.46 euros D 40.59 euros

(b) 1 D 190 yen, hence23 D 23 190 yen D 4370 yen

(c) 1 D 10.90 kronor, hence

6409.20 kronor D 6409.2010.90

D 588

(d) 1 D 1.52 dollars, hence90 D 90 1.52 dollars D $136.80

(e) 1 D 2.15 Swiss francs, hence2795 franc D 2795

2.15D 1300

Problem 15. Some approximate imperial tometric conversions are shown in Table 4.2

Table 4.2

length 1 inch D 2.54 cm1 mile D 1.61 km

weight 2.2 lb D 1 kg1 lb D 16 oz

capacity 1.76 pints D 1 litre8 pints D 1 gallon


Use the table to determine:

(a) the number of millimetres in 9.5 inches,

(b) a speed of 50 miles per hour inkilometres per hour,

(c) the number of miles in 300 km,

(d) the number of kilograms in 30 poundsweight,

(e) the number of pounds and ounces in42 kilograms (correct to the nearestounce),

(f) the number of litres in 15 gallons, and

(g) the number of gallons in 40 litres.

(a) 9.5 inches D 9.5 2.54 cm D 24.13 cm24.13 cm D 24.13 10 mm D 241.3 mm

(b) 50 m.p.h. D 50 1.61 km/h D 80.5 km=h(c) 300 km D 300

1.61miles D 186.3 miles

(d) 30 lb D 302.2

kg D 13.64 kg(e) 42 kg D 42 2.2 lb D 92.4 lb

0.4 lb D 0.4 16 oz D 6.4 oz D 6 oz, correctto the nearest ounce

Thus 42 kg D 92 lb 6 oz, correct to the near-est ounce.

(f) 15 gallons D 15 8 pints D 120 pints120 pints D 120

1.76litres D 68.18 litres

(g) 40 litres D 40 1.76 pints D 70.4 pints

70.4 pints D 70.48

gallons D 8.8 gallons


Exercise 15 Further problems conversiontables and charts

1. Currency exchange rates listed in a news-paper included the following:

Italy 1 D 1.48 euroJapan 1 D 185 yenAustralia 1 D 2.70 dollarsCanada 1 D $2.40Sweden 1 D 13.25 kronor

Calculate (a) how many Italian euros32.50 will buy, (b) the number ofCanadian dollars that can be purchasedfor 74.80, (c) the pounds sterling whichcan be exchanged for 14 040 yen, (d) thepounds sterling which can be exchangedfor 1754.30 Swedish kronor, and (e) theAustralian dollars which can be boughtfor 55

[(a) 48.10 euros (b) $179.52(c) 75.89 (d) 132.40(e) 148.50 dollars]

2. Below is a list of some metric to imperialconversions.

Length 2.54 cm D 1 inch1.61 km D 1 mile

Weight 1 kg D 2.2 lb 1 lb D 16 ounces

Capacity 1 litre D 1.76 pints

8 pints D 1 gallon

Use the list to determine (a) the numberof millimetres in 15 inches, (b) a speed of35 mph in km/h, (c) the number of kilo-metres in 235 miles, (d) the number ofpounds and ounces in 24 kg (correct tothe nearest ounce), (e) the number of kilo-grams in 15 lb, (f) the number of litres in1

engineering mathematics -...

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