Big Ideas Math: Modeling Real Life, Grade 7
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Big Ideas Math: Modeling Real Life, Grade 7 View details
4. Percents of Increase and Decrease
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Exercise 24 Page 258

Is the value of the new amount greater than or less than the value of the original amount?

Increase or Decrease? Increase
Percent of Change: 100 %

Practice makes perfect

We want to tell whether each percent change is an increase or decrease. Then, we want to find the percent change. Let's do it one at a time.

Percent Increase or Percent Decrease

Recall that if a new amount is greater than the original amount, the percent change is called a percent increase. If the new amount is less than the original amount, the percent change is called a percent decrease. Consider the given amounts. Original Amount:&1/4 [0.7em] New Amount:&1/2 Before we compare the fractions, let's create a common denominator. We are going to multiply the numerator and denominator of 12 by 2 and simplify.

1/2
1 * 2/2 * 2
2/4

Now we can see that the new amount is greater than the original amount because the fractions have the same denominator and the numerator of the second fraction is greater. 1/4 < 2/4 ⇔ 1 < 2 As a result, the percent change is an increase.

Finding the Percent Change

To determine the percent change p, we can use the following general formula. p % =Amount of change/Original amount From the given values, we can see the original amount was 14 and the new amount is 12, or 24. This is an increase in the amount. Let's find the amount of increase. 2/4- 1/4= 2-1/4 or 1/4 The difference between the new amount and the original amount is 14. Now we can use the formula.

Percent of change=Amount of increase/Original amount
Percent of change=14/14
Percent of change=1/1
Percent of change=1
Percent of change = 100 %

The percent increase is 100 %.