Chapter 4 - Proportions, Percents, and Solving Inequalities - 4.2 - Percents and Problem Solving - Problem Set 4.2 - Page 155: 32

The percentage of change in the number of phones sold between May and June is +24%, so it is a percent increase.

The cell phone store sold 200 phones in May and 248 phones in June. To find the percentage of change, we use the following formula: Percent of change = $\frac{New\ amount\ -\ Original\ amount}{Original\ amount}$ $\times$ 100% The new amount is 248, and the original amount is 200. We substitute these values into the equation to obtain: Percentage change = $\frac{248 - 200}{200}$ $\times$ 100% Percentage change = $\frac{48}{200}$ $\times$ 100% Percentage change = 0.24 $\times$ 100% Percentage change = 24%