7th Grade Math

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Proportions

PART A BCDE

Multi-Part

Lesson 1

GLE 0706.2.3

Develop an understanding of

and apply proportionality.

GLE 0706.2.4 Use ratios,

rates and percents to solve

single- and multi-step

problems in various contexts.

Also addresses GLE 0706.1.4,

SPI 0706.2.7.

Lesson 1A Proportions 265

Main Idea

Model proportions

using bar diagrams.

Unit Rates

MONEY When Jeremy gets his allowance, he

agrees to save part of it. His savings and expenses

are in the ratio 7 : 5. If his daily allowance is $3,

how much does he save each day?

What do you need to find? how much money Jeremy saves

each day

The ratio of savings to expenses is 7 to 5.

Savings

Expenses

Total

amount

= $3.00

Let x represent each part of a bar. Write an equation.

7 x + 5 x = 3 Write the equation.

12 x = 3 There are 12 parts in all.

12 x

_

12 =^

_^3

12 Division Property of Equality

x = _^14 or 0.25 Simplify.

Each part of the bar represents $0.25. Jeremy’s savings

are represented by 7 parts. 7 × $0.25 or $1.75

So, Jeremy saves $1.75 each day.

the Results

Use a bar diagram to solve.

1. ATHLETES The ratio of the number of boys to the number of girls
   on the swim team is 7 : 6. If there are 39 athletes on the swim
   team, how many more boys than girls are there?


2. DOGS In a dog kennel, the number of long-haired dogs and the
   number of short-haired dogs are in the ratio of 5 : 3. If there are
   20 long-haired dogs, how many dogs are there altogether?

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