Unit 11Units of Measurements

Presentation 1 Units and Measuring

Presentation 2 Upper and Lowers Bounds

Unit 11Units of Measurements

Units and Measuring

Different units can be used to measure the same quantities. It is important to use appropriate units. Some important units are listed below.

1 km1 m1 m1 cm1 tonne1 kg1 litre1m3

1cm3

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100010010001010001000100010001

m cm mm mm kg g ml litresml

What would be the best units to use when measuring the following:

a)The distance between Negril and Kingston

b)The width of a watch face

c)The mass of a person

d)The mass of a letter

e)The mass of a truck

f)The volume of medicine in a spoon

g)The volume of water in a swimming pool

km

cm or mm

kg

g

tonnes

ml

m3

Length in m Length in cm Length in mm

4

311

1500

8∙62

400 4000

31103∙11

1∙5 150

8620862

Unit 11Units of Measurements

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Units and Measuring

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Presentation 1 Units and Measuring

Presentation 2 Upper and Lower Bounds

Unit 11Units of Measurements

Upper and Lower Bounds

Measurements are not exactIf the length of a line is given as 11mm, then its length, in mm, lies between:

Note that the lower bound is less than or equal to the length whereas the upper bound is strictly greater than the length

10∙5 ≤ length < 11∙5

ExampleA line is measured as 12∙7cmState the range of values within which its real length, in cm, must lie.

Solution

12∙65 ≤ 12∙7 < 12∙75

A B

Area = cm2 Area = cm210 12

CD

Area = cm2 Area ≈ cm212∙5 14∙5

E

Area ≈ cm222

Unit 11Units of Measurements

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Upper and Lower Bounds

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Presentation 1 Units and Measuring

Presentation 2 Upper and Lower Bounds