1. Percent of Change
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2. Warm Up
Solve each problem. Round to the nearest hundredth. Show all work.
1). Wilma wants a bike that cost $ It is on sale for 20% off. How much will she pay for the bike?
2). How much will Wilma (from problem one) pay in total if sales tax is 6%?
3). Henry and his family bought pizza. It cost $32.00 for 4 pizzas. If they gave the delivery boy a 15% tip, how much did they pay in total?
4). How much tax would you pay on $7.80 if the tax rate is 6.5%?
$196
$207.76
$36.80
$0.51

3. Percent of Increase – When the new amount is more than the original.
Percent of Change is a ratio that compares the change in a quantity to the original amount.
new amount – original amount
Percent of Increase – When the new amount is more than the original.
Percent of Decrease- When the new amount is less than the original.

4. Example 1: Find the percent of change in tree height from year 1 to year 10. Round to the nearest whole percent if necessary.
Year Ten-9.6 ft.
Year One- 4 feet
140% increase

5. Example 2: Find the percent of change if the original price of a pair of shoes was $75 and the new price is $60.
20% decrease

6. 20% increase 40% increase 50% decrease 33% increase 71% decrease
Practice
Find the percent of change. Tell if it is an increase or decrease.
1). Original: 15 cupcakes
New: 18 cupcakes
2). Original: 100 marbles
New: 140 marbles
3). Original: $12
New: $6
4). Original: $240
New: $320
5). Original: 48 pencils
New: 14 pencils
20% increase
40% increase
50% decrease
33% increase
71% decrease

7. Closure
Give an example of when you find a percent of increase or decrease in real life.