wk2tuesday

Agenda 10/4/11

1. Review: Divisibility Rules 2. Discuss/Correct Quiz 3. Review: Reducing 4. Algebra: Introduction to Ratio and

Proportion

Divisibility Rules

Review- Divisible by 3?

5736

Divisible by 4?

2,245,264,580

Divisibility Rules

Divisible by 5?

942

Divisible by 6?

644

Divisibility Rules

Divisible by 7?

310

Divisible by 8?

8712

Nine

A number is divisible by 9 if the sum of the digits adds up to a multiple of nine.

9,243 is divisible by nine because the sum of the digits adds up to 18, which is a multiple of nine.

Ten

A number is evenly divisible by ten if the rightmost digit is zero.

648,375,939,578,340 is evenly divisible by ten because the rightmost digit is a zero.

Check

Which numbers are evenly divisible by nine?

8883

9001

109

Check

Which numbers are evenly divisible by ten?

657430

99548

1010101

Discuss Quiz

Review Word Problems

Remember the steps:

Step 1: Understand the question.

Step 2: Find the necessary information.

Step 3: Decide upon the calculation you need to make to answer the question.

Step 4: Does it make sense?

Reducing

When reducing fractions, you must divide both the top and bottom numbers by the same number until it cannot be divided further.

525

255

RATIO A ratio is a comparison of numbers by

division.

A ratio can be written with the word to, with a colon (:), or as a fraction.

Should always be reduced (simplifying)

Three Ways to Write a Ratio

3 to 2 3:2 3/2

RATIO TIPSThe numbers in a ratio MUST be written

in the order the problem asks for.

Always reduce a ratio to lowest terms.

When a ratio is an improper fraction, DO NOT change it to a mixed number.

Setting Up Ratios: Steps

1. Read the problem carefully.

2. Pay attention to the order the question wants you to write the ratio.

3. Set up the ratio appropriately.

4. REDUCE!!!!!

RATIO Evelyn earns $2400 a month. She pays $600 a

month in rent. What is the ratio of her income to her rent.

Make a ratio with her income first (in the numerator) and her rent second.

incomerent

2400600

246

41

RATIO In a factory, there are 150 men and 100

women working.

To compare these facts, write a ratio of men to women working in the factory.

menwomen

150100

1510

3 men2 women

Practice 1-6 pg 138

1. 24:30 =

200:125 =

28 = 21

Practice 1-6 pg 138

2. 3.4 = 1.7

4 to 1000 =

$560 to $320

Practice 1-6 pg 138

3. Alvaro makes $600 a week and saves $60 a week. What is the ratio of the amount he makes to the amount he saves?

Practice 1-6 pg 1384. For Alvaro, in problem 3,

what is the ratio of the amount he saves to the amount he makes?

Practice 1-6 pg 138 There are 24 students in Sam’s English class.

Four of the students speak Armenian as a first language. What is the ratio of Armenian speakers to the total number of students in the class?

Practice 1-6 pg 138

6. Anna drove 110 miles on 22 gallons of gas. What is the ratio of the distance she drove to the number of gallons of gas she used?

TWO-STEP RATIO PROBLEMS

When you are not given both numbers you need, you may have to determine one of the numbers.

TWO-STEP RATIO PROBLEMS On a test with 20 problems, Maceo got 2

problems wrong. What was the ratio of the number of problems he got right to the total number of problems?

Step 1: Find the number of problems he got right.

Step 2: Make a ratio of the number of problems he got right to the total number of problems.

Reduce.

20-2= 18problems right.

righttotal

1820

910

Exercise 2, page 139

1. A GED class of 20 students has 12 women. A.) What is the ratio of the number of

women to the total number of students? B.) What is the ratio of the number of men

to the total number of students? C.) What is the ratio of the number of men

to the number of women? D.) What is the ratio of the number of

women to the number of men?


2. At Baxter Electronics there are 105 union workers and 45 nonunion workers.

A.) What is the ratio of the number of union workers to the total number of workers?

B.) What is the ratio of the number of nonunion workers to the total number of workers?

C.) What is the ratio of the number union workers to the number of nonunion workers?

D.) What is the ratio to the number of workers to the number of union workers?


From a total yearly budget of $18,000,000, the city of McHenry spends $3,000,000 on education. What is the ratio of the amount spent on education to the amount not spent on education?


4. A math test of 50 questions included 15 fraction problems and 5 decimal problems. What is the ratio of the total number of fraction and decimal problems to the number of questions on the test?


5. There are 1213 registered voters in Paul’s village. During the last election 887 people actually voted. Which of the following is approximately the ratio of the number of people who voted to the total number of registered voters?