Intro to Proportions

Front

What is a proportion?

Back

A proportion is an equation that states that two ratios are equal.

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CCSS.7.RP.A.2A

Front

How do you set up a proportion?

Back

To set up a proportion, you can use the formula a/b = c/d, where a and b are the first ratio, and c and d are the second ratio.

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CCSS.7.RP.A.2C

Front

What does it mean to solve a proportion?

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Solving a proportion means finding the unknown value in the ratio that makes the two ratios equal.

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CCSS.7.EE.B.3

Front

If 14 out of 50 fish are trout, what is the ratio of trout to total fish?

Back

The ratio of trout to total fish is 14:50, which simplifies to 7:25.

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CCSS.6.RP.A.1

CCSS.6.RP.A.2

Front

How do you find the expected number of items using a proportion?

Back

To find the expected number, set up a proportion based on the known ratio and solve for the unknown.

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CCSS.7.RP.A.3

Front

What is the expected number of trout in a lake with a population of 7,500 if 14 out of 50 fish are trout?

Back

The expected number of trout is 2,100.

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CCSS.7.RP.A.3

Front

If 13 out of 20 homes have a personal computer, what is the ratio of homes with computers?

Back

The ratio is 13:20.

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CCSS.6.RP.A.1

CCSS.6.RP.A.2

Front

How many homes would you expect to have a personal computer on a street with 60 homes?

Back

You would expect 39 homes to have a personal computer.

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CCSS.6.RP.A.3B

Front

What is the ratio of dogs to cats in an animal shelter if there are 25 dogs and the ratio is 5:3?

Back

The ratio of dogs to cats is 5:3, so there are 15 cats.

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CCSS.6.RP.A.1

CCSS.6.RP.A.2

Front

How do you write a proportion to find the number of cats if there are 25 dogs?

Back

Set up the proportion 5/3 = 25/c and solve for c.

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CCSS.7.RP.A.3