1. Learn to solve problems involving percent of change.

2. Do Now
According to the U.S. Consumer Product Safety Commission, emergency rooms treated more than 50,000 skateboarding injuries in This was a 67% decrease from 150,000 skateboarding injuries in 1977.
What reasons could there be for the decrease in injuries?

3. Many times, percents are used to describe the amount of change that has occurred. You’ve seen it in advertising (“Now with 25% more stuff!!!). You see it in reports like the one about skateboarding. These percents are referred to as a percent of change.

4. the amount, stated as a percent, that a number increases or decreases.
Percent of change
the amount, stated as a percent, that a number increases or decreases.
Percent increase describes how much the original amount increases.
Percent decrease describes how much the original amount decreases.

5. Calculating the percent of change is similar to calculating regular percents.

6. Example A
Find the percent of change. Round answers to the nearest tenth of a percent, if necessary.
65 is decreased to 38.
% change = amount of change
original amount
65 – 38 = 27
x =
100 27 65
 41.5%
The percent of decrease is about 41.5%.

7. Example A continued
Find the percent of change. Round answers to the nearest tenth of a percent, if necessary.
41 is increased to 92.
% change = amount of change
original amount
92 – 41 = 51
x =
100 51 41
 124.4%
The percent of increase is about 124.4%.

8. You Try
Find the percent of change. Round answers to the nearest tenth of a percent, if necessary.
70 is decreased to 45.
The percent of decrease is about 35.7%.

9. You Try
Find the percent of change. Round answers to the nearest tenth of a percent, if necessary.
37 is increased to 56.
The percent of increase is about 51.4%

10. 270% increase 35% decrease Practice
The cost of gas went from $.98 per gallon in 2002 to $3.63 per gallon Find the percent of change.
A shirt you really wanted was originally priced at $45. It finally went on sale and now costs $ Find the percent of change.
270% increase
35% decrease
Find each percent increase or decrease to the nearest percent.
3. from 12 to from 1625 to 1400
5. from 37 to from 1.25 to 0.85
25% increase
14% decrease
238% increase
32% decrease

11. Lesson Quiz
Find each percent of change.
1. 10 is increased to 12.
2. 25 is increased to 45.
3. 10 is decreased to 1.
20%
80%
90%

12. Lesson Quiz for Student Response Systems
Identify the percent of change.
20 is increased to 22.
A. 10%
B. 20%
C. 30%
D. 40%

13. Lesson Quiz for Student Response Systems
2. Identify the percent of change.
30 is increased to 54.
A. 30%
B. 54%
C. 75%
D. 80%

14. Lesson Quiz for Student Response Systems
3. Identify the percent of change.
15 is decreased to 3.
A. 80%
B. 75%
C. 60%
D. 50%