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Big Ideas Math: Modeling Real Life, Grade 7

BI

Big Ideas Math: Modeling Real Life, Grade 7 View details

1. Ratios and Ratio Tables

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Exercise 17 Page 188

Use the portion where both values are known.

Feet	1/24	1/12	1/8	1/48
Inches	1/2	1	3/2	1/4

Equivalent Ratios: 124: 12, 112:1, 18: 32, and 148: 14

Practice makes perfect

We want to complete a table. We can use the portion where both values are known to find the missing values.

Feet	1/24		1/8
Inches	1/2	1		1/4

We know that 124 feet is the same as 1/2 inches. Let's write this as a ratio. 124feet/12inches or 124/12

We will use this rate to find the missing values.

First Value

We can find an equivalent ratio with a denominator of 1 to find how feet are the same as 1 inch.

124/12

a/b=a * 2/b * 2

124* 2/12* 2

Multiply

112/1

We found that 112 feet is the same as 1 inch.

Feet	1/24	1/12	1/8
Inches	1/2	1		1/4

Second Value

Now, we can find an equivalent ratio with a numerator of 18 to find how many inches are in 18 feet.

124/12

a/b=a * 3/b * 3

124* 3/12* 3

Calculate quotient

18/32

We found that 18 feet is the same as 32 inches.

Feet	1/24	1/12	1/8
Inches	1/2	1	3/2	1/4

Third Value

Now, we can find an equivalent ratio with a denominator of 14 to find how many feet are the same as 14 inches.

124/12

a/b=.a / 2./.b / 2.

124÷ 2/12÷ 2

Calculate quotient

148/14

We found that 148 feet is the same as 14 inches.

Feet	1/24	1/12	1/8	1/48
Inches	1/2	1	3/2	1/4

The equivalent ratios are 124: 12, 112:1, 18: 32, and 148: 14.

Subchapter links

Try It p.184-185

Self-Assessment for Concept & Skills p.185

Self-Assessment for Problem Solving p.186

Review & Refresh p.187

Concept, Skills, & Problem Solving p.187-188