1. PRE-ALGEBRA

2. Lesson 6-7 Warm-Up

3. PRE-ALGEBRA What is “percent of change”? How do you find the percent of increase or decrease? percent of change: percent of quantity increase or decrease from the original amount. To find the percent of increase or decrease, use a proportion or find the difference between the change and the original amount and divide by the original amount Rule: Example: Find the percent of decrease from 70 to 63. Method 1: Proportion #% Part (Known)7 x Whole (Unknown)70 100 = Proportion. 7 70 x 100 70 x = 7 100 Cross products are equal. 70 - 63 = 7 Find the amount of decrease = Divide both sides by 70.. 70x 70 700 70 x = 10 70 to 63 is a 10% decrease 1 1 10 1 Percent of Change (6-7)

4. PRE-ALGEBRA How do you find the percent of a number? Method 2: Divide the difference by 100 Find the difference (subtract) between the original amount the new amount. Then, divide by the original amount 70 - 63 70 0 1 _. Multiply by 100 or move the decimal 2 places to the right to change a decimal into a percent. = Fraction bars also indicate division, so divide 7 by 70. 7 70 0.1 70 to 63 is a 10% decrease 1 0. % Fill in skipped blank spaces with zeros. Percent of Change (6-7)

5. PRE-ALGEBRA Find the percent of increase from 8 to 9.6. amount of increase = 9.6 – 8 = 1.6 = 0.2 = 0. 2 0. = 20% The percent of increase from 8 to 9.6 is 20%. percent of increase = amount of increase original amount = 1.6 8 Percent of Change LESSON 6-7 Additional Examples

6. PRE-ALGEBRA In a given year, Hillsboro had a total of 7.5 in. of rain by March 1 and a total of 22.5 in. by July 1. Find the percent of increase from 7.5 to 22.5. amount of increase = 22.5 – 7.5 = 15 = 2. = 2 0 0.% = 200% The percent of increase from March 1 to July 1 was 200%. percent of increase = amount of increase original amount = 15 7.5 Percent of Change LESSON 6-7 Additional Examples

7. PRE-ALGEBRA Find the percent of decrease from 1,250 to 1,120. amount of decrease = 1,250 – 1,120 = 130 = 0.104 = 0 1 0 4 = 10.4% percent of decrease = amount of decrease original amount = 130 1,250 Percent of Change LESSON 6-7 Additional Examples

8. PRE-ALGEBRA Solve. 1.Find the percent of increase from 22 to 63. 2.Find the percent of decrease from 6.3 to 2.2. 3.A surgeon performed 62 operations in 1991. He performed 342 in 2001. Find the percent of increase. 186.4% 451.6% 65.1% Lesson Quiz Percent of Change LESSON 6-7