经济学原理第三版习题答案.docx

经济学原理第三版习题答案.docx

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经济学原理第三版习题答案

SOLUTIONSTOTEXTPROBLEMS:

QuickQuizzes

1.Figure1showsthedemandcurveforturkey.ThepriceofturkeyisP1andtheconsumersurplusthatresultsfromthatpriceisdenotedCS.Consumersurplusmeasuresbuyers’willingnesstopay（measuredbythedemandcurve）minustheamountthebuyersactuallypay.

Figure1

Figure2

2.Figure2showsthesupplycurveforturkey.ThepriceofturkeyisP1andtheproducersurplusthatresultsfromthatpriceisdenotedPS.Producersurplusmeasurestheamountsellersarepaidforagoodminusthesellers’cost（measuredbythesupplycurve）.

Figure3

3.Figure3showsthesupplyanddemandforturkey.ThepriceofturkeyisP1,consumersurplusisCS,andproducersurplusisPS.Producingmoreturkeywouldlowertotalsurplusbecausethevaluetobuyerswouldbelessthanthecosttosellers.

QuestionsforReview

1.Buyers'willingnesstopay,consumersurplus,andthedemandcurveareallcloselyrelated.Theheightofthedemandcurverepresentsthewillingnesstopayofthebuyers.Consumersurplusistheareabelowthedemandcurveandabovetheprice,whichequalseachbuyer'swillingnesstopaylessthepriceofthegood.

2.Sellers'costs,producersurplus,andthesupplycurveareallcloselyrelated.Theheightofthesupplycurverepresentsthecostsofthesellers.Producersurplusistheareabelowthepriceandabovethesupplycurve,whichequalsthepriceminuseachsellers'costs.

Figure4

3.Figure4showsproducerandconsumersurplusinasupply-and-demanddiagram.

4.Anallocationofresourcesisefficientifitmaximizestotalsurplus,thesumofconsumersurplusandproducersurplus.Butefficiencymaynotbetheonlygoalofeconomicpolicymakers;theymayalsobeconcernedaboutequity−thefairnessofthedistributionofwell-being.

5.Theinvisiblehandofthemarketplaceguidestheself-interestofbuyersandsellersintopromotinggeneraleconomicwell-being.Despitedecentralizeddecisionmakingandself-interesteddecisionmakers,freemarketsleadtoanefficientoutcome.

6.Twotypesofmarketfailurearemarketpowerandexternalities.Marketpowermaycausemarketoutcomestobeinefficientbecausewhenfirmsinfluencepricestheycausepriceandquantitytodifferfromthelevelstheywouldbeunderperfectcompetition,whichkeepstotalsurplusfrombeingmaximized.Externalitiesaresideeffectsthatarenottakenintoaccountbybuyersandsellers.Asaresult,thefreemarketdoesnotmaximizetotalsurplus.

ProblemsandApplications

1.IfanearlyfreezeinCaliforniasoursthelemoncrop,thesupplycurveforlemonsshiftstotheleft,asshowninFigure5.TheresultisariseinthepriceoflemonsandadeclineinconsumersurplusfromA+B+CtojustA.SoconsumersurplusdeclinesbytheamountB+C.

Figure5

Inthemarketforlemonade,thehighercostoflemonsreducesthesupplyoflemonade,asshowninFigure6.TheresultisariseinthepriceoflemonadeandadeclineinconsumersurplusfromD+E+FtojustD,alossofE+F.Notethataneventthataffectsconsumersurplusinonemarketoftenhaseffectsonconsumersurplusinothermarkets.

Figure6

2.AriseinthedemandforFrenchbreadleadstoanincreaseinproducersurplusinthemarketforFrenchbread,asshowninFigure7.Theshiftofthedemandcurveleadstoanincreasedprice,whichincreasesproducersurplusfromareaAtoareaA+B+C.

Figure7

TheincreasedquantityofFrenchbreadbeingsoldincreasesthedemandforflour,asshowninFigure8.Asaresult,thepriceofflourrises,increasingproducersurplusfromareaDtoD+E+F.Notethataneventthataffectsproducersurplusinonemarketleadstoeffectsonproducersurplusinrelatedmarkets.

Figure8

3.a.Bert’sdemandscheduleis:

Price

QuantityDemanded

Morethan$7

0

$5to$7

1

$3to$5

2

$1to$3

3

$1orless

4

Bert’sdemandcurveisshowninFigure9.

Figure9

b.Whenthepriceofabottleofwateris$4,Bertbuystwobottlesofwater.HisconsumersurplusisshownasareaAinthefigure.Hevalueshisfirstbottleofwaterat$7,butpaysonly$4forit,sohasconsumersurplusof$3.Hevalueshissecondbottleofwaterat$5,butpaysonly$4forit,sohasconsumersurplusof$1.ThusBert’stotalconsumersurplusis$3+$1=$4,whichistheareaofAinthefigure.

c.Whenthepriceofabottleofwaterfallsfrom$4to$2,Bertbuysthreebottlesofwater,anincreaseofone.HisconsumersurplusconsistsofbothareasAandBinthefigure,anincreaseintheamountofareaB.Hegetsconsumersurplusof$5fromthefirstbottle（$7valueminus$2price）,$3fromthesecondbottle（$5valueminus$2price）,and$1fromthethirdbottle（$3valueminus$2price）,foratotalconsumersurplusof$9.Thusconsumersurplusrisesby$5（whichisthesizeofareaB）whenthepriceofabottleofwaterfallsfrom$4to$2.

4.a.Ernie’ssupplyscheduleforwateris:

Price

QuantitySupplied

Morethan$7

4

$5to$7

3

$3to$5

2

$1to$3

1

Lessthan$1

0

Ernie’ssupplycurveisshowninFigure10.

Figure10

b.Whenthepriceofabottleofwateris$4,Erniesellstwobottlesofwater.HisproducersurplusisshownasareaAinthefigure.Hereceives$4forhisfirstbottleofwater,butitcostsonly$1toproduce,soErniehasproducersurplusof$3.Healsoreceives$4forhissecondbottleofwater,whichcosts$3toproduce,sohehasproducersurplusof$1.ThusErnie’stotalproducersurplusis$3+$1=$4,whichistheareaofAinthefigure.

c.Whenthepriceofabottleofwaterrisesfrom$4to$6,Erniesellsthreebottlesofwater,anincreaseofone.HisproducersurplusconsistsofbothareasAandBinthefigure,anincreasebytheamountofareaB.Hegetsproducersurplusof$5fromthefirstbottle（$6priceminus$1cost）,$3fromthesecondbottle（$6priceminus$3cost）,and$1fromthethirdbottle（$6priceminus$5price）,foratotalproducersurplusof$9.Thusproducersurplusrisesby$5（whichisthesizeofareaB）whenthepriceofabottleofwaterrisesfrom$4to$6.

5.a.FromErnie’ssupplyscheduleandBert’sdemandschedule,thequantitydemandedandsuppliedare:

Price

QuantitySupplied

QuantityDemanded

$2

1

3

4

2

2

6

3

1

Onlyapriceof$4bringssupplyanddemandintoequilibrium,withanequilibriumquantityof2.

b.Atapriceof$4,consumersurplusis$4andproducersurplusis$4,asshowninproblems3and4.Totalsurplusis$4+$4=$8.

c.IfErnieproducedonefewerbottle,hisproducersurpluswoulddeclineto$3,asshowninproblem4.IfBertconsumedonefewerbottle,hisconsumersurpluswoulddeclineto$3,asshowninproblem3.Sototalsurpluswoulddeclineto$3+$3=$6.

d.IfErnieproducedoneadditionalbottleofwater,hiscostwouldbe$5,butthepriceisonly$4,sohisproducersurpluswoulddeclineby$1.IfBertconsumedoneadditionalbottleofwater,hisvaluewouldbe$3,butthepriceis$4,sohisconsumersurpluswoulddeclineby$1.Sototalsurplusdeclinesby$1+$1=$2.

6.a.Theeffectoffallingproductioncostsinthemarketforstereosresultsinashifttotherightinthesupplycurve,asshowninFigure11.Asaresult,theequilibriumpriceofstereosdeclinesandtheequilibriumquantityincreases.

b.ThedeclineinthepriceofstereosincreasesconsumersurplusfromareaAtoA+B+C+D,anincreaseintheamountB+C+D.Priortotheshiftinsupply,producersurpluswasareasB+E（theareaabovethesupplycurveandbelowtheprice）.Aftertheshiftinsupply,producersurplusisareasE+F+G.SoproducersurpluschangesbytheamountF+G–B,whichmaybepositiveornegative.Theincreaseinquantityincreasesproducersurplus,whilethedeclineinthepricereducesproducersurplus.SinceconsumersurplusrisesbyB+C+DandproducersurplusrisesbyF+G–B,totalsurplusrisesbyC+D+F+G.

c.Ifthesupplyofstereosisveryelastic,thentheshiftofthesupplycurvebenefitsconsumersmost.Totakethemostdramaticcase,supposethesupplycurvewerehorizontal,asshowninFigure12.Thenthereisnoproducersurplusatall.Consumerscaptureallthebenefitsoffallingproductioncosts,withconsumersurplusrisingfromareaAtoareaA+B.

Figure11

Figure12

7.Figure13showssupplyanddemandcurvesforhaircuts.Supplyequalsdemandataquantityofthreehaircutsandapricebetween$4and$5.FirmsA,C,andDshouldcutthehairofRiki,Jerry,andMontel.Oprah’swillingnesstopayistoolowandfirmB’scostsaretoohigh,sotheydonotparticipate.Themaximumtotalsurplusistheareabetweenthedemandandsupplycurves,whichtotals$11（$8valueminus$2costforthefirsthaircut,plus$7valueminus$3costforthesecond,plus$5valueminus$4costforthethird）.

Figure13

8.a.Theeffectoffallingproductioncostsinthemarketforcomputersresultsinashifttotherightinthesupplycurve,asshowninFigure14.Asaresult,theequilibriumpriceofcomputersdeclinesandtheequilibriumquantityincreases.ThedeclineinthepriceofcomputersincreasesconsumersurplusfromareaAtoA+B+C+D,anincreaseintheamountB+C+D.

Figure14

Priortotheshiftinsupply,producersurpluswasareasB+E（theareaabovethesupplycurveandbelowtheprice）.Aftertheshiftinsupply,producersurplusisareasE+F+G.SoproducersurpluschangesbytheamountF+G–B,whichmaybepositiveornegative.Theincreaseinquantityincreasesproducersurplus,whilethedeclineinthepricereducesproducersurplus.SinceconsumersurplusrisesbyB+C+DandproducersurplusrisesbyF+G–B,totalsurplusrisesbyC+D+F+G.

Figure15

b.Since