曼昆经济学原理习题解答58章.docx

曼昆经济学原理习题解答58章.docx

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曼昆经济学原理习题解答58章

CH5~6作業解答

CH5

1.a.Mysterynovelshavemoreelasticdemandthanrequiredtextbooksbecausemysterynovelshaveclosesubstitutesandarealuxurygood,whilerequiredtextbooksareanecessitywithnoclosesubstitutes.Ifthepriceofmysterynovelsweretorise,readerscouldsubstituteothertypesofnovels,orbuyfewernovelsaltogether.Butifthepriceofrequiredtextbooksweretorise,studentswouldhavelittlechoicebuttopaythehigherprice.Thus,thequantitydemandedofrequiredtextbooksislessresponsivetopricethanthequantitydemandedofmysterynovels.

b.Beethovenrecordingshavemoreelasticdemandthanclassicalmusicrecordingsingeneral.Beethovenrecordingsareanarrowermarketthanclassicalmusicrecordings,soitiseasiertofindclosesubstitutesforthem.IfthepriceofBeethovenrecordingsweretorise,peoplecouldsubstituteotherclassicalrecordings,likeMozart.Butifthepriceofallclassicalrecordingsweretorise,substitutionwouldbemoredifficult.（Atransitionfromclassicalmusictorapisunlikely!

）Thus,thequantitydemandedofclassicalrecordingsislessresponsivetopricethanthequantitydemandedofBeethovenrecordings.

c.Subwayridesduringthenextfiveyearshavemoreelasticdemandthansubwayridesduringthenextsixmonths.Goodshaveamoreelasticdemandoverlongertimehorizons.Ifthefareforasubwayridewastorisetemporarily,consumerscouldnotswitchtootherformsoftransportationwithoutgreatexpenseorgreatinconvenience.Butifthefareforasubwayridewastoremainhighforalongtime,peoplewouldgraduallyswitchtoalternativeformsoftransportation.Asaresult,thequantitydemandedofsubwayridesduringthenextsixmonthswillbelessresponsivetochangesinthepricethanthequantitydemandedofsubwayridesduringthenextfiveyears.

d.Rootbeerhasmoreelasticdemandthanwater.Rootbeerisaluxurywithclosesubstitutes,whilewaterisanecessitywithnoclosesubstitutes.Ifthepriceofwaterweretorise,consumershavelittlechoicebuttopaythehigherprice.Butifthepriceofrootbeerweretorise,consumerscouldeasilyswitchtoothersodasorbeverages.Sothequantitydemandedofrootbeerismoreresponsivetochangesinpricethanthequantitydemandedofwater.

2.a.Forbusinesstravelers,thepriceelasticityofdemandwhenthepriceofticketsrisesfrom$200to$250is[（2,000–1,900）/1,950]/[（250–200）/225]=0.05/0.22=0.23.Forvacationers,thepriceelasticityofdemandwhenthepriceofticketsrisesfrom$200to$250is[（800–600）/700]/[（250–200）/225]=0.29/0.22=1.32.

b.Thepriceelasticityofdemandforvacationersishigherthantheelasticityforbusinesstravelersbecausevacationerscanchooseasubstitutemoreeasilythanbusinesstravelers.Forexample,vacationerscanchooseadifferentmodeoftransportation（likedrivingortakingthetrain）,adifferentdestination,adifferentdeparturedate,andadifferentreturndate.Theymayalsochoosetonottravelatall.Businesstravelersarelesslikelytodosobecausetheirschedulesarelessadaptable.

3.a.Thepercentagechangeinpriceisequalto（2.20–1.80）/2.00x100=20%.Ifthepriceelasticityofdemandis0.2,quantitydemandedwillfallby4%intheshortrun[0.20  0.20].Ifthepriceelasticityofdemandis0.7,quantitydemandedwillfallby14%inthelongrun[0.70.2].

b.Overtime,consumerscanmakeadjustmentstotheirhomesbypurchasingalternativeheatsourcessuchasnaturalgasorelectricfurnaces.Thus,theycanrespondmoreeasilytothechangeinthepriceofheatingoilinthelongrunthanintheshortrun.

4.Ifquantitydemandedfell,pricemusthaveincreasedaccordingtothelawofdemand.Forapriceincreasetoincreasetotalrevenue,thepercentageincreaseinthepricemustbegreaterthanthepercentagedeclineinquantitydemanded.Therefore,demandisinelastic.

6.a.Ifyourincomeis$10,000,yourpriceelasticityofdemandasthepriceofDVDsrisesfrom$8to$10is[（40–32）/36]/[（10–8）/9]=0.22/0.22=1.Ifyourincomeis$12,000,theelasticityis[（50–45）/47.5]/[（10–8）/9]=0.11/0.22=0.5.

b.Ifthepriceis$12,yourincomeelasticityofdemandasyourincomeincreasesfrom$10,000to$12,000is[（30–24）/27]/[（12,000–10,000）/11,000]=0.22/0.18=1.22.Ifthepriceis$16,yourincomeelasticityofdemandasyourincomeincreasesfrom$10,000to$12,000is[（12–8）/10]/[（12,000–10,000）/11,000]=0.40/0.18=2.22.

8.a.Thepercentagechangeinprice（usingthemidpointformula）is（1.50–1.25）/（1.375）×100%=18.18%.Therefore,thepriceelasticityofdemandis4.3/18.18=0.24,whichisveryelastic.

b.Becausethedemandisinelastic,theTransitAuthority'srevenueriseswhenthefarerises.

c.Theelasticityestimatemightbeunreliablebecauseitisonlythefirstmonthafterthefareincrease.Astimegoesby,peoplemayswitchtoothermeansoftransportationinresponsetothepriceincrease.Sotheelasticitymaybelargerinthelongrunthanitisintheshortrun.

10.a.Withapriceelasticityofdemandof0.4,reducingthequantitydemandedofcigarettesby20%requiresa50%increaseinprice,because20/50=0.4.Withthepriceofcigarettescurrently$2,thiswouldrequireanincreaseinthepriceto$3.33apackusingthemidpointmethod（notethat（$3.33–$2）/$2.67=.50）.

b.Thepolicywillhavealargereffectfiveyearsfromnowthanitdoesoneyearfromnow.Theelasticityislargerinthelongrun,becauseitmaytakesometimeforpeopletoreducetheircigaretteusage.Thehabitofsmokingishardtobreakintheshortrun.

c.Becauseteenagersdonothaveasmuchincomeasadults,theyarelikelytohaveahigherpriceelasticityofdemand.Also,adultsaremorelikelytobeaddictedtocigarettes,makingitmoredifficulttoreducetheirquantitydemandedinresponsetoahigherprice.

CH6

2.a.TheimpositionofabindingpricefloorinthecheesemarketisshowninFigure4.Intheabsenceofthepricefloor,thepricewouldbeP1andthequantitywouldbeQ1.WiththefloorsetatPf,whichisgreaterthanP1,thequantitydemandedisQ2,whilequantitysuppliedisQ3,sothereisasurplusofcheeseintheamountQ3–Q2.

Figure4

b.Theproducers’complaintthattheirtotalrevenuehasdeclinediscorrectifdemandiselastic.Withelasticdemand,thepercentagedeclineinquantitywouldexceedthepercentageriseinprice,sototalrevenuewoulddecline.

c.Ifthegovernmentpurchasesallthesurpluscheeseatthepricefloor,producersbenefitandtaxpayerslose.ProducerswouldproducequantityQ3ofcheese,andtheirtotalrevenuewouldincreasesubstantially.However,consumerswouldbuyonlyquantityQ2ofcheese,sotheyareinthesamepositionasbefore.Taxpayerslosebecausetheywouldbefinancingthepurchaseofthesurpluscheesethroughhighertaxes.

3.a.TheequilibriumpriceofFrisbeesis$8andtheequilibriumquantityissixmillionFrisbees.

b.Withapricefloorof$10,thenewmarketpriceis$10becausethepricefloorisbinding.Atthatprice,onlytwomillionFrisbeesaresold,becausethatisthequantitydemanded.

c.Ifthere’sapriceceilingof$9,ithasnoeffect,becausethemarketequilibriumpriceis$8,whichisbelowtheceiling.Sothemarketpriceis$8andthequantitysoldissixmillionFrisbees.

6.Thepricewillrisebylessthan$500.Theburdenofanytaxissharedbybothproducersandconsumersthepricepaidbyconsumersrisesandthepricereceivedbyproducersfalls,withthedifferencebetweenthetwoequaltotheamountofthetax.Theonlyexceptionswouldbeifthesupplycurvewereperfectlyelasticorthedemandcurvewereperfectlyinelastic,inwhichcaseconsumerswouldbearthefullburdenofthetaxandthepricepaidbyconsumerswouldrisebyexactly$500.

.

7.a.Itdoesnotmatterwhetherthetaxisimposedonproducersorconsumerstheeffectwillbethesame.Withnotax,asshowninFigure7,thedemandcurveisD1andthesupplycurveisS1.Ifthetaxisimposedonproducers,thesupplycurveshiftsleftbytheamountofthetax（50cents）toS2.ThentheequilibriumquantityisQ2,thepricepaidbyconsumersisP2,andthepricereceived（aftertaxesarepaid）byproducersisP2–50cents.Ifthetaxisinsteadimposedonconsumers,thedemandcurveshiftsleftbytheamountofthetax（50cents）toD2.Theleftwardshiftinthedemandcurve（whenthetaxisimposedonconsumers）isexactlythesamemagnitudeastheleftwardshiftinthesupplycurvewhenthetaxisimposedonproducers.Soagain,theequilibriumquantityisQ2,thepricepaidbyconsumersisP2（includingthetaxpaidtothegovernment）,andthepricereceivedbyproducersisP2–50cents

Figure7Figure8

b.Themoreelasticthedemandcurveis,themoreeffectivethistaxwillbeinreducingthequantityofgasolineconsumed.Greaterelasticityofdemandmeansthatquantityfallsmoreinresponsetotheriseintheprice.Figure8illustratesthisresult.DemandcurveD1representsanelasticdemandcurve,whiledemandcurveD2ismoreinelastic.Thetaxwillcauseagreaterdeclineinthequantitysoldwhendemandiselastic.

c.Theconsumersofgasolinearehurtbythetaxbecausetheygetlessgasolineatahigherprice.

d.Workersintheoilindustryarehurtbythetaxaswell.Withalowerquantityofgasolinebeingproduced,someworkersmaylosetheirjobs.Withalowerpricereceivedbyproducers,wagesofworkersmightdecline.

CH7

1.a.Consumersurplusisequaltowillingnesstopayminusthepricepaid.Therefore,Melissa’swillingnesstopaymustbe$200（$120+$80）.

b.Herconsumersurplusatapriceof$90wouldbe$200−$90=$110.

c.IfthepriceofaniPhonew