Elementary Algebra

Published by Cengage Learning
ISBN 10: 1285194055
ISBN 13: 978-1-28519-405-9

Chapter 4 - Proportions, Percents, and Solving Inequalities - 4.2 - Percents and Problem Solving - Problem Set 4.2 - Page 156: 49


The percent change in Susan's electric bill from June to July is 25%. It is a percent increase.

Work Step by Step

The bill for the month of July was 80.00 dollars. This was 16.00 more than the bill for the month of June, which means that the bill for the month of June was 80.00 - 16.00 = 64.00 dollars. To find the percent change, we use the following formula: percent change = $\frac{New\ amount\ -\ Original\ amount}{Original\ amount}$ $\times$ 100% The previous bill was 64.00 dollars while the new bill was 80.00 dollars. Substituting these values into the formula yields: percent change = $\frac{80.00\ -\ 64.00}{64.00}$ $\times$ 100% percent change = $\frac{16.00}{64.00}$ $\times$ 100% percent change = 0.25 $\times$ 100% percent change = 25% Because the percent change is a positive number, it is a percent increase.
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