Big Ideas Math: Modeling Real Life, Grade 7
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Big Ideas Math: Modeling Real Life, Grade 7 View details
2. The Percent Proportion
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Exercise 12 Page 245

The percent proportion is a proportion that equates a part of a whole to a percent out of 100.

Answer: 84
Model:

Practice makes perfect

We want to find the number which is 120% of 70 by using a model. We can split the model into 20% intervals. There are 5 such intervals in 100%, which represents the whole 70. Let's find 120% of 70!

We found that 84 is 120 % of 70.

Checking Our Answer

We can check our answer by solving the percent proportion. The percent proportion is a proportion that sets the ratio of a part of a whole equal to the ratio of a percent out of 100. We can represent a is p percent of wwith the given proportion. part/whole=percent/100 ⇔ a/w=p/100 We can find what 120% of 70 is by thinking about 120 as the percent and 70 as the whole. Let's substitute p= 120 and w= 70 into the formula and solve for a using the Properties of Equality.
a/w=p/100
a/70=120/100
Solve for a
a/70* 70=120/100 * 70
a=120/100 * 70
a=120* 70/100
a=8400/100
a= 84
Knowing the value of a, let's look at the completed percent proportion. 84/70=120/100