Exercise 19 Page 149

Let's start by recalling that a percent of change is a ratio that compares the change in quantity to the original amount. If the original quantity is increased, then it is called a percent of increase. If the original quantity is decreased, then it is called a percent of decrease. To determine the percent of change, we can use the following formula. Percent of change =Amount of change/Original amount In this case, the original quantity is $ 240, and the new quantity is $ 320. We can find the amount of change by subtracting the less value from the greater one. Amount of change = $ 320 - $ 240 = $ 80 Now let's use the formula to find the percent of change. To make the math easier, we can ignore the units for now.

To write the decimal as a percent, we need to move the decimal point two places to the right and write the percent symbol.

We found that the percent of change is about 33 %. Finally, let's state whether the percent of change is an increase or a decrease. To do so, we need to compare the original quantity with the new quantity. ccc Original quantity & & New quantity [0.5em] $ 240 & < & $ 320 Since the new quantity is greater than the original quantity, this is a percent of increase.