7th Grade Math

21. MATH IN THE MEDIA Find examples of data reflecting change over a
    period of time in a newspaper or magazine, on television, or on the
    Internet. Determine the percent of change. Explain whether the data
    show a percent of increase or decrease.


22. SALES Use the graph shown to

Sale of CDs (in millions)

Drop in CD Sales

2011 283 million

2012 271 million

Year

270 275 280 285 290

find the percent of change in CD

sales from 2011 to 2012.

23 SHOES Shoe sales for a certain

company were $25.9 billion. Sales

are expected to increase by about

20% in the next year. Find the

projected amount of shoe sales

next year.

24. BABYSITTING The table shows how many hours
    Month WorkedHours
    April 40
    May 32
    June 42

Catalina spent babysitting during the months of

April and May.

a. If Catalina charges $6.50 per hour, what is the

percent of change in the amount of money earned

from April to May? Is it a change of increase or

decrease?

b. What is the percent of change in the amount of money earned from

May to June? Round to the nearest percent if needed. Is it a change of

increase or decrease?

c. Compare the percent of change from April to May and then May to

June. Which is a greater percent of change?

C 25. NUMBER SENSE The costs of two different sound systems were decreased

by $10. The original costs of the systems were $90 and $60, respectively.

Without calculating, which had a greater percent of decrease? Explain.

26. FIND THE ERROR Dario is finding the percent of
    change from $52 to $125. Find his mistake and
    correct it.

__$125 - $52

$125

≈ 0.58

or 58%

27. E WRITE MATH Explain how, when comparing data, two amounts of
    change can be the same but the percents of change can be different.

Lesson 3B Applying Percents 349

2

22

Percent of Change

Always use the

original amount as

the whole when

finding percent of

change.

345_363_C06_L3_895130.indd 349 12/30/09 4:08 PM