1. NS1.6 Calculate the percentage of increase and decrease of a quantity. NS1.7 Solve problems that involve discounts, markups, commissions, and profit and compute simple and compound interest. California Standards SECTION 6-5: Applying Percent of Increase and Decrease $%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$

2. Percents can be used to describe a change. Percent of change is the ratio of the amount of change to the original amount. Percent of increase describes how much the original amount increases. Percent of decrease describes how much the original amount decreases. amount of change original amount percent of change =

3. Find the percent of increase or decrease from 16 to 12. Additional Example 1A: Finding Percent of Increase or Decrease This is a percent of decrease. 16 – 12 = 4First find the amount of change. amount of decrease original amount 4 16 Set up the ratio. Find the decimal form. Write as a percent. = 0.25 = 25% 4 16 From 16 to 12 is a 25% decrease.

4. Find the percent increase or decrease from 45 to 54. This is a percent of increase. 54 – 45 = 9First find the amount of change. amount of increase original amount 9 45 Set up the ratio. Additional Example 1B: Finding Percent of Increase or Decrease Find the decimal form. Write as a percent. = 0.20 = 20% 9 45 From 45 to 54 is a 20% increase.

5. Find the percent increase or decrease from 50 to 65. This is a percent of increase. Check It Out! Example 1A 65 – 50 = 15First find the amount of change. amount of increase original amount 15 50 Set up the ratio. Find the decimal form. Write as a percent. = 0.30 = 30% 15 50 From 50 to 65 is a 30% increase.

6. Find the percent of increase or decrease from 20 to 17. Check It Out! Example 1B This is a percent of decrease. 20 – 17 = 3First find the amount of change. amount of decrease original amount 3 20 Set up the ratio. Find the decimal form. Write as a percent. = 0.15 = 15% 3 20 From 20 to 17 is a 15% decrease.

7. When Jim was exercising, his heart rate went from 72 beats per minute to 98 beats per minute. What was the percent increase to the nearest tenth of a percent? Additional Example 2: Health Application 26 72 Set up the ratio. 98 – 72 = 26 First find the amount of change. amount of increase original amount Find the decimal form. Write as a percent.  0.361  36.1% 26 72 From 72 to 98 increases by about 36.1%.

8. In 2005, a certain stock was worth $1.25 a share. In 2006, the same stock was worth $0.85 a share. What was the percent decrease? Check It Out! Example 2 1.25 – 0.85 = 0.40 First find the amount of change. amount of decrease original amount 1.25 0.40 Set up the ratio. Find the decimal form. Write as a percent. = 0.32 = 32% 1.25 0.40 The value of the stock decreased by 32%.

9. Discount is the difference between the regular price and the sale price of an item. You can use percent of decrease to find discounts. Markup is the difference between the wholesale cost and the retail price of an item. You can use percent of increase to find markups.

10. Sarah bought a DVD player originally priced at $450 that was on sale for 20% off. What was the discounted price? Additional Example 3A: Finding Discount and Markup (450)(0.20) = 90 Find 20% of $450. This is the amount of discount. 450 – 90 = 360 Subtract $90 from $450. Method 1: Multiply, then subtract. The discounted price was $360.

11. Additional Example 3B: Finding Discount and Markup (85)(0.40) = 34Find 40% of $85. This is the amount of markup. 85 + 34 = 119 Add $34 to $85. Method 1: Multiply, then add. Mr. Olsen has a computer business in which he sells everything 40% above the wholesale price. If he purchased a printer for $85 wholesale, what will be the retail price? The retail price is $119.

12. SUMMARY Percents can be used to describe a change. Percent of change is the ratio of the amount of change to the original amount. Percent of increase describes how much the original amount _________. Percent of decrease describes how much the original amount ________. amount of ______ original ______ percent of change = WORDS Decreases Amount Increases change

13. SUMMARY Discount is the difference between the _______ price and the ____ price of an item. You can use percent of decrease to find discounts. Markup is the difference between the _________ cost and the ______ price of an item. You can use percent of increase to find markups. WORDS Wholesale Regular Retail Sale