1. EXAMPLE 1
Finding a Percent of Decrease
During the summer, a bear’s heart rate is about 60 beats per minute, but it can drop to as low as 8 beats per minute during the winter. What is the percent of change in a bear’s heart rate from the summer rate to the winter low rate?
Bears
SOLUTION
To find the percent of decrease, use the percent of change equation.

2. Finding a Percent of Decrease
EXAMPLE 1
Finding a Percent of Decrease p% =
60 – 8 60
Write amount of decrease and divide by original amount. = 52 60
Subtract. =
0.86 _
Write fraction as a decimal.
86.67%
Write decimal as a percent.
The percent of decrease is about 86.7%.
ANSWER

3. Finding a Percent of Increase
EXAMPLE 2
Finding a Percent of Increase
A school had 825 students enrolled last year. This year, 870 students are enrolled. Find the percent of increase to the nearest tenth.
School Enrollment
SOLUTION p% =
870 – 825
825
Write amount of increase and divide by original amount. =
825 45
Subtract. =
0.0545 __
Write fraction as a decimal.
5.45%
Write decimal as a percent.

4. EXAMPLE 2
Finding a Percent of Increase
The percent of increase is about 5.5%.
ANSWER

5. Using Percent of Increase
EXAMPLE 3
Using Percent of Increase
From October to November one year, attendance at Everglades National Park increased about 27.4%. There were 59,084 visitors in October. To the nearest hundred, how many people visited in November?
National Parks
SOLUTION
STEP 1
Find the increase.
Increase =
27.4% of 59,084 =
0.274( 59,084)
Write 27.4% as a decimal.
16,189
Multiply.

6. EXAMPLE 3
Using Percent of Increase
STEP 2
Add the increase to the original amount.
New Amount
59,084
16,189
75,273 + =
ANSWER
About 75,300 people visited the park in November.

7. GUIDED PRACTICE for Examples 1, 2 and 3
Tell whether the change is an increase or decrease. Then find the percent of change. Round to the nearest percent. 1.
Original amt = 50
New amt = 36
The change is a decrease since the new amount is less than the original amount p% =
50 – 36 50
Write amount of decrease and divide by original amount. = 50 14
Subtract. =
0.28
Write fraction as a decimal.
28% =
Write decimal as a percent.

8. GUIDED PRACTICE for Examples 1, 2 and 3 2. Original amt = 10
New amt = 29.5
The change is an increase since the new amount is greater than the original amount p% =
29.5 – 10 10
Write amount of decrease and divide by original amount. = 10
19.5
Subtract. =
1.95
Write fraction as a decimal.
195% =

9. GUIDED PRACTICE for Examples 1, 2 and 3 3. Original amt = 90
New amt = 110
The change is an increase since the new amount is greater than the original amount p% =
110 – 90 90
Write amount of decrease and divide by original amount. = 90 20
Subtract. =
0.222
Write fraction as a decimal.
22% =

10. GUIDED PRACTICE
for Examples 1, 2 and 3
What If? In Example 3, suppose the attendance decreased by about 11%. Approximate, to the nearest thousand, the attendance in November 4.
SOLUTION
Find the decrease.
decrease
= 11% of 59,084
= 0.11(59,084) =

11. GUIDED PRACTICE
for Examples 1, 2 and 3
Subtract the decrease to the original amount.
New amount
59,084 – 6499
52,585
ANSWER
About 53,000 people visited the park in November.