To find the percent of change in the number of units sold between 2004 and 2006 for each format, we can use the formula:
Percent change = ((new value - old value) / old value) * 100
a. CD:
Percent change between 2004 and 2006:
= ((614.9 - 767.0) / 767.0) * 100
= (-152.1 / 767.0) * 100
= -19.8% (rounded to the nearest tenth)
Downloaded:
Percent change between 2004 and 2006:
= ((586.4 - 139.4) / 139.4) * 100
= (447.0 / 139.4) * 100
= 320.7% (rounded to the nearest tenth)
Video:
Percent change between 2004 and 2006:
= ((23.1 - 32.8) / 32.8) * 100
= (-9.7 / 32.8) * 100
= -29.6% (rounded to the nearest tenth)
b. The percent of change in part a is:
- For CD: a percent of decrease
- For Downloaded: a percent of increase
- For Video: a percent of decrease
This means that CD sales decreased by 19.8% between 2004 and 2006, downloaded sales increased by 320.7%, and video sales decreased by 29.6% during the same time period.