#9

Pays4%simpleinterestMax.insured:$250,000

Pays3.2%simpleinterestMax.insured:$500,000

SimpleInterestI = Prt

A B

PAmountInvested

r%Interest

I =Prtt =1year

BANKA(max.$250,000)

x 4%=0.04 x(0.04)

BANKB(max.$500,000)

500,000 – x 3.2%=0.032 (500,000 – x)(0.032)

InterestearnedinBankA+InterestearnedinBankB=Totalinterestearned

0.04x+(0.032)(500,000– x)=18,500

#11

Adults+ children=600peopleAdultticketscost$9andChildrenticketscost$6.

Number Price perticket TotalSales

Adults 600 – c $9 9(600 – c)

Children c $6 6c

Totalticketsalesofadults+totalticketsalesofchildren=totalsales

9(600– c)+6c =4800

#13

original-adult’sdrinksolutionhas30%glucose

wateraddedtosolution-toreduce%ofglucose-waterhas0%glucose

newsolution-child’sdrink7ounceshas20%glucose

Amount(ounces)

%Glucose TotalGlucose

Adult’sDrink 7– x 30%=0.30 (7– x)(0.30)

Water x 0%=0 0

Child’sDrink 7 20%=0.20 7(0.20)

Totalglucoseinadult’sdrink+glucoseinwater=totalglucoseinchild’sdrink

(7– x)(0.30)+0=7(0.20)

#15

Britishsterlingsilverhas7.5%copper

PurecopperHas100%copper

Newmixture200gramsthathas10%copper

Amount(grams) %copper TotalCopper

BritishSterling 200 – x 7.5%=0.075 (200 – x)(0.075)

PureCopper x 100%=1 x(1)

NewAlloy 200 10%=0.10 200(0.10)

CopperinBritishSterling+purecopper=copperinnewalloy

(0.075)(200– x)+x =(0.10)(200)

#18

Runningatarateof6mphStarts5minuteslaterRunningatarateof8mph

Ratex Time=Distance(samedistanceforbothrunners)

r=rate t=time d=distance

First Runner 6mph t + 6(t +)

SecondRunner 8mph t 8t

Sincetheyranthesamedistance:Distanceofthefirstrunner=distanceofthesecondrunner

6(t +)=8t

#31

Boytakes90minutes Sistertakes60minutes Togethertakesxminutes

Job(mowing)

Time(minutes)

Rate(1lawnin?min.)

Boy 1lawn 90

Sister 1lawn 60

Together 1lawn x

Rateoftheboy+rateofthesister=ratetogether