经济学原理 曼昆版 课后习题英文答案.docx

经济学原理 曼昆版 课后习题英文答案.docx

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经济学原理曼昆版课后习题英文答案

1）ProblemsandApplications

1.a.Afamilydecidingwhethertobuyanewcarfacesatradeoffbetweenthecostofthecarandotherthingstheymightwanttobuy.Forexample,buyingthecarmightmeantheymustgiveupgoingonvacationforthenexttwoyears.Sotherealcostofthecaristhefamily'sopportunitycostintermsofwhattheymustgiveup.

b.ForamemberofCongressdecidingwhethertoincreasespendingonnationalparks,thetradeoffisbetweenparksandotherspendingitemsortaxcuts.Ifmoremoneygoesintotheparksystem,thatmaymeanlessspendingonnationaldefenseoronthepoliceforce.Or,insteadofspendingmoremoneyontheparksystem,taxescouldbereduced.

c.Whenacompanypresidentdecideswhethertoopenanewfactory,thedecisionisbasedonwhetherthenewfactorywillincreasethefirm'sprofitscomparedtootheralternatives.Forexample,thecompanycouldupgradeexistingequipmentorexpandexistingfactories.Thebottomlineis:

Whichmethodofexpandingproductionwillincreaseprofitthemost?

d.Indecidinghowmuchtoprepareforclass,aprofessorfacesatradeoffbetweenthevalueofimprovingthequalityofthelecturecomparedtootherthingsshecoulddowithhertime,suchasworkingonadditionalresearch.

2.Whenthebenefitsofsomethingarepsychological,suchasgoingonavacation,itisn'teasytocomparebenefitstocoststodetermineifit'sworthdoing.Buttherearetwowaystothinkaboutthebenefits.Oneistocomparethevacationwithwhatyouwoulddoinitsplace.Ifyoudidn'tgoonvacation,wouldyoubuysomethinglikeanewsetofgolfclubs?

Thenyoucandecideifyou'dratherhavethenewclubsorthevacation.Asecondwayistothinkabouthowmuchworkyouhadtodotoearnthemoneytopayforthevacation;thenyoucandecideifthepsychologicalbenefitsofthevacationwereworththepsychologicalcostofworking.

3.Ifyouarethinkingofgoingskiinginsteadofworkingatyourpart-timejob,thecostofskiingincludesitsmonetaryandtimecosts,plustheopportunitycostofthewagesyou'regivingupbynotworking.Ifthechoiceisbetweenskiingandgoingtothelibrarytostudy,thenthecostofskiingisitsmonetaryandtimecostsplusthecosttoyouofgettingalowergradeinyourcourse.

4.Ifyouspend$100nowinsteadofinvestingitforayearandearning5percentinterest,youaregivinguptheopportunitytospend$105ayearfromnow.Theideathatmoneyhasatimevalueisthebasisforthefieldoffinance,thesubfieldofeconomicsthathastodowithpricesoffinancialinstrumentslikestocksandbonds.

5.Thefactthatyou'vealreadysunk$5millionisn'trelevanttoyourdecisionanymore,sincethatmoneyisgone.Whatmattersnowisthechancetoearnprofitsatthemargin.Ifyouspendanother$1millionandcangeneratesalesof$3million,you'llearn$2millioninmarginalprofit,soyoushoulddoso.Youarerighttothinkthattheprojecthaslostatotalof$3million（$6millionincostsandonly$3millioninrevenue）andyoushouldn'thavestartedit.That'strue,butifyoudon'tspendtheadditional$1million,youwon'thaveanysalesandyourlosseswillbe$5million.Sowhatmattersisnotthetotalprofit,buttheprofityoucanearnatthemargin.Infact,you'dpayupto$3milliontocompletedevelopment;anymorethanthat,andyouwon'tbeincreasingprofitatthemargin.

6.Harrysuggestslookingatwhetherproductivitywouldriseorfall.Productivityiscertainlyimportant,sincethemoreproductiveworkersare,thelowerthecostpergallonofpotion.Harrywantstolookataveragecost.ButbothHarryandRonaremissingtheothersideoftheequation¾revenue.Afirmwantstomaximizeitsprofits,soitneedstoexaminebothcostsandrevenues.Thus,Hermioneisright¾it’sbesttoexaminewhethertheextrarevenuewouldexceedtheextracosts.Inaddition,Hermioneistheonlyonewho’sthinkingatthemargin.

7.a.Sinceapersongetsfewerafter-taxSocialSecuritybenefitsthegreaterishisorherincome,there'sanincentivenottosaveforretirement.Ifyousavealot,yourincomewillbehigher,andyouwon'tgetasmuchafter-taxSocialSecurityincomeassomeonewhodidn'tsaveasmuch.TheunintendedconsequenceofthetaxationofSocialSecuritybenefitsistoreducesaving;yettheSocialSecuritysystemarosebecauseofworriesthatpeoplewouldn’tsaveenoughforretirement.

b.Forthesamereason,you'lltendnottowork（ornotworkasmuch）afterage65.Themoreyouwork,theloweryourafter-taxSocialSecuritybenefitswillbe.ThusthetaxationofSocialSecuritybenefitsdiscouragesworkeffortafterage65.

8.a.Whenwelfarerecipientswhoareabletoworkhavetheirbenefitscutoffaftertwoyears,theyhavegreaterincentivetofindjobsthaniftheirbenefitsweretolastforever.

b.Thelossofbenefitsmeansthatsomeonewhocan'tfindajobwillgetnoincomeatall,sothedistributionofincomewillbecomelessequal.Buttheeconomywillbemoreefficient,sincewelfarerecipientshaveagreaterincentivetofindjobs.Thusthechangeinthelawisonethatincreasesefficiencybutreducesequity.

9.Byspecializingineachtask,youandyourroommatecanfinishthechoresmorequickly.Ifyoudividedeachtaskequally,itwouldtakeyoumoretimetocookthanitwouldtakeyourroommate,anditwouldtakehimmoretimetocleanthanitwouldtakeyou.Byspecializing,youreducethetotaltimespentonchores.

Similarly,countriescanspecializeandtrade,makingbothbetteroff.Forexample,supposeittakesSpanishworkerslesstimetomakeclothesthanFrenchworkers,andFrenchworkerscanmakewinemoreefficientlythanSpanishworkers.ThenSpainandFrancecanbothbenefitifSpanishworkersproducealltheclothesandFrenchworkersproduceallthewine,andtheyexchangesomewineforsomeclothes.

10.a.Beingacentralplanneristough!

ToproducetherightnumberofCDsbytherightartistsanddeliverthemtotherightpeoplerequiresanenormousamountofinformation.YouneedtoknowaboutproductiontechniquesandcostsintheCDindustry.Youneedtoknoweachperson'smusicaltastesandwhichartiststheywanttohear.Ifyoumakethewrongdecisions,you'llbeproducingtoomanyCDsbyartiststhatpeopledon'twanttohear,andnotenoughbyothers.

b.YourdecisionsabouthowmanyCDstoproducecarryovertootherdecisions.YouhavetomaketherightnumberofCDplayersforpeopletouse.IfyoumaketoomanyCDsandnotenoughcassettetapes,peoplewithcassetteplayerswillbestuckwithCDstheycan'tplay.Theprobabilityofmakingmistakesisveryhigh.Youwillalsobefacedwithtoughchoicesaboutthemusicindustrycomparedtootherpartsoftheeconomy.Ifyouproducemoresportsequipment,you'llhavefewerresourcesformakingCDs.SoalldecisionsabouttheeconomyinfluenceyourdecisionsaboutCDproduction.

11.a.Efficiency:

ThemarketfailurecomesfromthemonopolybythecableTVfirm.

b.Equity

c.Efficiency:

Anexternalityarisesbecausesecondhandsmokeharmsnonsmokers.

d.Efficiency:

ThemarketfailureoccursbecauseofStandardOil'smonopolypower.

e.Equity

f.Efficiency:

There'sanexternalitybecauseofaccidentscausedbydrunkdrivers.

12.a.Ifeveryonewereguaranteedthebesthealthcarepossible,muchmoreofournation'soutputwouldbedevotedtomedicalcarethanisnowthecase.Wouldthatbeefficient?

Ifyouthinkthatcurrentlydoctorsformamonopolyandrestricthealthcaretokeeptheirincomeshigh,youmightthinkefficiencywouldincreasebyprovidingmorehealthcare.Butmorelikely,ifthegovernmentmandatedincreasedspendingonhealthcare,theeconomywouldbelessefficientbecauseitwouldgivepeoplemorehealthcarethantheywouldchoosetopayfor.Fromthepointofviewofequity,ifpoorpeoplearelesslikelytohaveadequatehealthcare,providingmorehealthcarewouldrepresentanimprovement.Eachpersonwouldhaveamoreevensliceoftheeconomicpie,thoughthepiewouldconsistofmorehealthcareandlessofothergoods.

b.Whenworkersarelaidoff,equityconsiderationsarguefortheunemploymentbenefitssystemtoprovidethemwithsomeincomeuntiltheycanfindnewjobs.Afterall,nooneplanstobelaidoff,sounemploymentbenefitsareaformofinsurance.Butthere’sanefficiencyproblem¾whyworkifyoucangetincomefordoingnothing?

Theeconomyisn’toperatingefficientlyifpeopleremainunemployedforalongtime,andunemploymentbenefitsencourageunemployment.Thus,there’satradeoffbetweenequityandefficiency.Themoregenerousareunemploymentbenefits,thelessincomeislostbyanunemployedperson,butthemorethatpersonisencouragedtoremainunemployed.Sogreaterequityreducesefficiency.

13.SinceaverageincomeintheUnitedStateshasroughlydoubledevery35years,wearelikelytohaveabetterstandardoflivingthanourparents,andamuchbetterstandardoflivingthanourgrandparents.Thisismainlytheresultofincreasedproductivity,sothatanhourofworkproducesmoregoodsandservicesthanitusedto.Thusincomeshavecontinuouslyrisenovertime,ashasthestandardofliving.

14.IfAmericanssavemoreanditleadstomorespendingonfactories,therewillbeanincreaseinproductionandproductivity,sincethesamenumberofworkerswillhavemoreequipmenttoworkwith.Thebenefitsfromhigherproductivitywillgotoboththeworkers,whowillgetpaidmoresincethey'reproducingmore,andthefactoryowners,whowillgetareturnontheirinvestments.There'snosuchthingasafreelunch,though,becausewhenpeoplesavemore,they'regivingupspending.Theygethigherincomesatthecostofbuyingfewergoods.

15.a.