Percent of Change Percent of Increase Percent of

Percent of Change Percent of Increase Percent of Decrease Percent Error

Vocabulary • percent of change: the amount, stated as a percent, that a number increases or decreases • percent of increase: when the original amount increases, the percent of change is called a percent of increase. • percent of decrease: when the original amount decreases, the percent of change is called a percent of decrease. • percent error: the percent that an estimated quantity differs from the actual

Finding Percent of Change amount of change (subtract) original amount Then convert the decimal to a percent!

Identify if the percent of change is an increase or decrease. Then find the percent of change. Round to the nearest hundredth if necessary.

Example #1 12 inches to 48 inches amount of change original amount 36 12 INCREASE! = 3 3 = 300% 48 – 12 12

Example #2 71 miles to 42. 5 miles amount of change original amount 28. 5 71 DECREASE! = 71 – 42. 5 0. 4014 = 40. 14% 71

Example #3 ¼ to ½ amount of change original amount INCREASE! = ¼ ¼ 1 = 100% 1 ½-¼ ¼

Example #4 Find the new amount: 10 meters increased by 25% Find 25% of 10. 10 x 0. 25 = 2. 5 Increase 10 by 2. 5. 10 + 2. 5 = 12. 5 meters

Example #5 The table shows population data for a community. Find the percent of change from 2005 to 2012. amount of change original amount 21, 000 119, 000 = Year Population 2005 119, 000 2012 140, 000 – 119, 000 0. 17647 = 17. 65%

Example #5 Use this percent of change to predict the population in 2019. 17. 65% Year Population 2005 119, 000 2012 140, 000 2019 ? 140, 000 increased by 17. 65% Find 17. 65% of 140, 000 x 0. 1765 = 24, 710 Increase 140, 000 by 24, 710. 140, 000 + 24, 710 = 164, 710

Finding the Percent of Error amount of error (subtract) actual amount Then convert the decimal to a percent!

Example #6 You estimate that the grade you got on the math test is an 81. The actual grade is an 87. Find the percent error. amount of error actual amount 6 87 = 87 - 81 0. 06896 = 6. 90% 87

Try This! Find the percent of change. Round to the nearest tenth, if necessary. 1) 180 is decreased to 140. 2) 55 is increased to 90.

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