1. Chapters 8.5 & 8.6 Problem Solving with percents Exploring percent of increase or decrease

2. Objectives I will use a problem solving plan to solve percent problems I will use percents to find discounts

3. Finding Discount When an item is “on sale,” the difference between the regular price and the sale price is called the discount. To find the discount percent, use the regular price as the base. For instance, if a $36 book is on sale for $27, then the discount is $9, and the discount percent is … =0.25 = 25 % Divide discount by regular price Rewrite in decimal form Rewrite in percent form

4. Finding a discount percent Last week you bought a sweatshirt on sale for $16.80. This week you visit the store again and find that the sweatshirt is back at the regular price of $22.68. What was the discount percent? The discount is 22.68 – 16.80 = 5.88 Now use the formula for the discount percent 25.9% The discount percent is about 25.9% Subtract sale price from regular price Divide discount by regular price Write in percent form

5. Give it a try! An advertisement states that a car on sale has been marked down $3,167.50. It also states that this was a 15% discount. What was the original price? Step 1: Use formula: Discount = 3,167.50 Percent = 15 Formula Substitute Solve for p Original price of car

6. Chapter 3.6 – Percent of Increase and Decrease Objectives: I will calculate percent of increase I will calculate percent of decrease

7. Percent of increase and percent of decrease A percent of increase and percent of decrease tells how much a quantity has changed. Formula Percent of Increase – if quantity increases Percent of Decrease – if quantity decreases

8. Finding a percent of increase There was 2.2 million computers used in public schools in 1991 and 2 million in 1990. Find the percent of increase. Larger # - Smaller # Original amount Simplify Divide Change to percent. There was a 10% increase.

9. Finding a percent of decrease In 1985 the coast to coast phone rates were $0.48 per minute. In 1987 the cost was $0.33 per minute. Find the percent of decrease from 1985 to 1987. Larger # - Smaller # Original amount (1985 comes before 1987) Simplify Convert to percent. There was a 31.25% decrease.

10. Give it a try! Decide whether the change is a percent increase or percent decrease and find the percent. A. Before 12, After 15B. Before 6, After 4 % increase 25% % decrease 33.33%