NAME DATE SECTION Intro to Exponential Functions – Day 8 Recalling Percent Change Wheels A scooter costs $160. For each question, show your reasoning. 1. The cost of a pair of roller skates is 20% of the cost of the scooter. How much do the roller skates cost? 2. A bicycle costs 20% more than the scooter. How much does the bicycle cost? 3. A skateboard costs 25% less than the bicycle. How much does the skateboard cost? Taxes and Sales 1. You need to pay 8% tax on a car that costs $12,000. What will you end up paying in total? Show your reasoning. 2. Burritos are on sale for 30% off. Your favorite burrito normally costs $8.50. How much does it cost now? Show your reasoning. 3. A pair of shoes that originally cost $79 are on sale for 35% off. Does the expression 0.65(79) represent the sale price of the shoes (in dollars)? Explain your reasoning.

Intro to Exponential Functions – Day 8 · Intro to Exponential Functions – Day 8 Recalling Percent Change Wheels A scooter costs $160. For each question, show your reasoning

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NAME DATE SECTION

IntrotoExponentialFunctions–Day8

RecallingPercentChange

Wheels

Ascootercosts$160.

Foreachquestion,showyourreasoning.

1. Thecostofapairofrollerskatesis20%ofthecostofthescooter.Howmuchdotherollerskatescost?

2. Abicyclecosts20%morethanthescooter.Howmuchdoesthebicyclecost?

3. Askateboardcosts25%lessthanthebicycle.Howmuchdoestheskateboardcost?

TaxesandSales1. Youneedtopay8%taxonacarthatcosts$12,000.Whatwillyouenduppayingin

total?Showyourreasoning.

2. Burritosareonsalefor30%off.Yourfavoriteburritonormallycosts$8.50.Howmuchdoesitcostnow?Showyourreasoning.

3. Apairofshoesthatoriginallycost$79areonsalefor35%off.Doestheexpression0.65(79)representthesalepriceoftheshoes(indollars)?Explainyourreasoning.

Page 2: Intro to Exponential Functions – Day 8 · Intro to Exponential Functions – Day 8 Recalling Percent Change Wheels A scooter costs $160. For each question, show your reasoning

ExpressingPercentIncreaseandDecrease

Completethetablesothateachrowhasadescriptionandtwodifferentexpressionsthatanswerthequestionaskedinthedescription.Thesecondexpressionshoulduseonlymultiplication.Bepreparedtoexplainhowthetwoexpressionsareequivalent.

descriptionandquestion expression1expression2(usingonlymultiplication)

Aone-nightstayatahotelinAnaheim,CAcosts$160.Hotelroomoccupancytaxis15%.Whatisthetotalcostofaone-nightstay?

160+ (0.15) ⋅ 160

Teachersreceive30%educatorsdiscountatamuseum.Anadultticketcosts$24.Howmuchwouldateacherpayforadmissionintothemuseum?

(0.7) ⋅ 24

Thepopulationofacitywas842,000tenyearsago.Thecitynowhas2%morepeoplethanithadthen.Whatisthepopulationofthecitynow?

Afteramajorhurricane,46%ofthe90,500householdsonanislandlosttheiraccesstoelectricity.Howmanyhouseholdsstillhaveelectricity?

754− (0.21) ⋅ 754

Twoyearsago,thenumberofstudentsinaschoolwas150.Lastyear,thestudentpopulationincreased8%.Thisyear,itincreasedabout8%again.Whatisthenumberofstudentsthisyear?

Page 3: Intro to Exponential Functions – Day 8 · Intro to Exponential Functions – Day 8 Recalling Percent Change Wheels A scooter costs $160. For each question, show your reasoning

Day8Summary

Wecanwritedifferentexpressionstocalculatepercentincreaseanddecrease.

Supposeanewphonecosts$360andisonsaleat25%offtheregularprice.Onewaytocalculatethisistofirstfind25%of360,whichis90,andthensubtract$90from$360togetasalepriceof$270.Thesecalculationscanberecordedinthisway:

360− (0.25) ⋅ 360 = 270

Anotherwaytorepresentthiscalculationistonoticethatsubtracting25%ofthecostisequivalenttofinding75%ofthecost.Usingthedistributiveproperty,weknowthat360− (0.25) ⋅ 360canberewrittenas(1− 0.25) ⋅ 360,whichisequalto(0.75) ⋅ 360.