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.

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

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.

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

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.

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.

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.

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% =

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% =

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) = 6499.24

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.