1. Percent of Change Lesson 7.5 OBJ: To find the percent of change in a quantity.

2. Percent of Change Indicates how much a quantity increases or decreases with respect to the original amount. Indicates how much a quantity increases or decreases with respect to the original amount. If the new amount is greater than the original amount than it is a percent of increase. If the new amount is greater than the original amount than it is a percent of increase. If the new amount is less than the original amount than it is a percent of decrease. If the new amount is less than the original amount than it is a percent of decrease.

3. Percent of Change The percent of change is the ratio of the amount of increase or decrease to the original amount. The percent of change is the ratio of the amount of increase or decrease to the original amount. Percent of change or Percent of change or p% = Amount of increase or decrease p% = Amount of increase or decrease original amount original amount

4. Find the percent of increase 1. Original: 20; New: 25 2. Original: 150; New: 189 3. Original: 55; New: 143

5. Find the Percent of Decrease 1. Original: 20; New: 15 2. Original: 75; New: 35 3. Original: 102; New: 51

6. Finding a New Amount If you know the original amount and the percent of change, you can find the new amount. First multiply the percent of change by the original amount to find the amount of change. Then increase or decrease the original amount by the amount of change. If you know the original amount and the percent of change, you can find the new amount. First multiply the percent of change by the original amount to find the amount of change. Then increase or decrease the original amount by the amount of change.

7. Examples Increase 45 by 20% Increase 45 by 20% 20% x 45 =.20 x 45 = 9 20% x 45 =.20 x 45 = 9 45 + 9 = 54 45 + 9 = 54 Decrease 85 by 28% Decrease 85 by 28% 28% x 85 =.28 x 85 = 23.8 85 – 23.8 = 61.2

8. More Examples 1. At its first visit to a veterinarian, a puppy weighted 28 pounds. Three months later, the puppy weighed 46 pounds. Find the percent of increase in its weight. 2. Find the percent of decrease from 250 to 149.

9. Examples 3. An annual concert was attended by 4212 people last year. This year, the number attending increased by about 14% over last year. How many people attended the concert this year? 4. Last month, a restaurant charged $12.95 for a seafood pasta dinner. This month, the owner has new menus printed, wit all dinner prices increase by 12%. What is the new price for the seafood pasta dinner?

10. Homework Text p. 355-356, #’s 7-21all problems. You must show all work. Text p. 355-356, #’s 7-21all problems. You must show all work.