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Math / Period NameChapter 6, Section 5 Percents of Increase & DecreaseVocabularyDefinitionFormulaPercent of changeThe percent that a quantity changes from the original amount% of change=amount of changeoriginal amount * 100 Percent of IncreaseWhen the original amount is increased % increase=NEW AMOUNT-original amountoriginal amount*100Percent of DecreaseWhen the original amount is decreased% decrease=original amount-NEW AMOUNToriginal amount*100Percent ErrorThe percent of an ESTIMATED quantity that differs from the actual amountpercent error=actual-estimatedactual amount*100Finding the Percent of Change:DayHours OnlineSaturday8Sunday10.5The table shows the numbers of hours a 7th grader spent online last weekend. What is the percent of change in the time online from Saturday to Sunday?Is this an INCREASE or a DECREASE?The number on Sunday was greater, so the change is a percent of increase.% of increase=NEW AMOUNT-original amountoriginal amount1.)Substitute:10.5-882.)Subtract: 2.583.)Solve:0.31254.) Write as a Percent:31.25%Practice:Find the percent of change. Round to the nearest tenth of a percent if necessary.1.)10 inches to 25 inches2.)57 people to 65 peopleIs this an increase or decrease? Is this an increase or decrease? Finding the Percent of Change:55769127112000The bar graph shows a softball player’s home run totals. What was the percent of change from 2012 to 2013?Is this an INCREASE or a DECREASE?The number in 2013 was lower than 2012, so the change is a percent of decrease.% of decrease=amount of change-NEW AMOUNToriginal amount1.)Substitute:28-20282.)Subtract: 8283.)Solve:≈0.2864.) Write as a Percent:≈28.6%Practice:Find the percent of change. Round to the nearest tenth of a percent if necessary.1.)50 pounds to 35 pounds2.)72 songs to 63 songsIs this an increase or decrease? Is this an increase or decrease? Finding the Percent Error:You estimate that the length of your classroom is 16 feet. The actual length is 21 feet. Find the percent error.First, find the amount of the error by subtracting: 21 – 16 = 5.percent error=actual-estimatedactual amount1.)Substitute:5212.)Solve:≈0.2383.) Write as a Percent:≈23.8%Practice:Find the percent error. Round to the nearest tenth of a percent if necessary.1.)You estimate that 200 people attended a school concert. The actual attendance was 240 people.2.)You estimate that a baby pig weighs 20 pounds. The actual weight of the baby pig is 16 pounds. ................
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