曼昆经济学原理微观经济学英文版习题答案考试章节筛选.docx

曼昆经济学原理微观经济学英文版习题答案考试章节筛选.docx

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曼昆经济学原理微观经济学英文版习题答案考试章节筛选

曼昆经济学原理微观经济学英文版

课后习题答案（考试章节筛选）

UNIT1

SOLUTIONSTOTEXTPROBLEMS:

QuickQuizzes

1.Thefourprinciplesofeconomicdecisionmakingare:

（1）peoplefacetradeoffs;

（2）thecostofsomethingiswhatyougiveuptogetit;（3）rationalpeoplethinkatthemargin;and（4）peoplerespondtoincentives.Peoplefacetradeoffsbecausetogetonethingthattheylike,theyusuallyhavetogiveupanotherthingthattheylike.Thecostofsomethingiswhatyougiveuptogetit,notjustintermsofmonetarycostsbutallopportunitycosts.Rationalpeoplethinkatthemarginbytakinganactionifandonlyifthemarginalbenefitsexceedthemarginalcosts.Peoplerespondtoincentivesbecauseastheycomparebenefitstocosts,achangeinincentivesmaycausetheirbehaviortochange.

2.Thethreeprinciplesconcerningeconomicinteractionsare:

（1）tradecanmakeeveryonebetteroff;

（2）marketsareusuallyagoodwaytoorganizeeconomicactivity;and（3）governmentscansometimesimprovemarketoutcomes.Tradecanmakeeveryonebetteroffbecauseitallowscountriestospecializeinwhattheydobestandtoenjoyawidervarietyofgoodsandservices.Marketsareusuallyagoodwaytoorganizeeconomicactivitybecausetheinvisiblehandleadsmarketstodesirableoutcomes.Governmentscansometimesimprovemarketoutcomesbecausesometimesmarketsfailtoallocateresourcesefficientlybecauseofanexternalityormarketpower.

3.Thethreeprinciplesthatdescribehowtheeconomyasawholeworksare:

（1）acountry’sstandardoflivingdependsonitsabilitytoproducegoodsandservices;

（2）pricesrisewhenthegovernmentprintstoomuchmoney;and（3）societyfacesashort-runtradeoffbetweeninflationandunemployment.Acountry’sstandardoflivingdependsonitsabilitytoproducegoodsandservices,whichinturndependsonitsproductivity,whichisafunctionoftheeducationofworkersandtheaccessworkershavetothenecessarytoolsandtechnology.Pricesrisewhenthegovernmentprintstoomuchmoneybecausemoremoneyincirculationreducesthevalueofmoney,causinginflation.Societyfacesashort-runtradeoffbetweeninflationandunemploymentthatisonlytemporaryandpolicymakershavesomeabilitytoexploitthisrelationshipusingvariouspolicyinstruments.

QuestionsforReview

1.Examplesoftradeoffsincludetimetradeoffs（suchasstudyingonesubjectoveranother,orstudyingatallcomparedtoengaginginsocialactivities）andspendingtradeoffs（suchaswhethertouseyourlasttendollarsonpizzaoronastudyguideforthattougheconomicscourse）.

2.Theopportunitycostofseeingamovieincludesthemonetarycostofadmissionplusthetimecostofgoingtothetheaterandattendingtheshow.Thetimecostdependsonwhatelseyoumightdowiththattime;ifit'sstayinghomeandwatchingTV,thetimecostmaybesmall,butifit'sworkinganextrathreehoursatyourjob,thetimecostisthemoneyyoucouldhaveearned.

3.Themarginalbenefitofaglassofwaterdependsonyourcircumstances.Ifyou'vejustrunamarathon,oryou'vebeenwalkinginthedesertsunforthreehours,themarginalbenefitisveryhigh.Butifyou'vebeendrinkingalotofliquidsrecently,themarginalbenefitisquitelow.Thepointisthateventhenecessitiesoflife,likewater,don'talwayshavelargemarginalbenefits.

4.Policymakersneedtothinkaboutincentivessotheycanunderstandhowpeoplewillrespondtothepoliciestheyputinplace.Thetext'sexampleofseatbeltsshowsthatpolicyactionscanhavequiteunintendedconsequences.Ifincentivesmatteralot,theymayleadtoaverydifferenttypeofpolicy;forexample,someeconomistshavesuggestedputtingknivesinsteeringcolumnssothatpeoplewilldrivemuchmorecarefully!

Whilethissuggestionissilly,ithighlightstheimportanceofincentives.

5.Tradeamongcountriesisn'tagamewithsomelosersandsomewinnersbecausetradecanmakeeveryonebetteroff.Byallowingspecialization,tradebetweenpeopleandtradebetweencountriescanimproveeveryone'swelfare.

6.The"invisiblehand"ofthemarketplacerepresentstheideathateventhoughindividualsandfirmsareallactingintheirownself-interest,pricesandthemarketplaceguidethemtodowhatisgoodforsocietyasawhole.

7.Thetwomaincausesofmarketfailureareexternalitiesandmarketpower.Anexternalityistheimpactofoneperson’sactionsonthewell-beingofabystander,suchasfrompollutionorthecreationofknowledge.Marketpowerreferstotheabilityofasingleperson（orsmallgroupofpeople）toundulyinfluencemarketprices,suchasinatownwithonlyonewelloronlyonecabletelevisioncompany.Inaddition,amarketeconomyalsoleadstoanunequaldistributionofincome.

8.Productivityisimportantbecauseacountry'sstandardoflivingdependsonitsabilitytoproducegoodsandservices.Thegreateracountry'sproductivity（theamountofgoodsandservicesproducedfromeachhourofaworker'stime）,thegreaterwillbeitsstandardofliving.

9.Inflationisanincreaseintheoveralllevelofpricesintheeconomy.Inflationiscausedbyincreasesinthequantityofanation'smoney.

10.Inflationandunemploymentarenegativelyrelatedintheshortrun.Reducinginflationentailscoststosocietyintheformofhigherunemploymentintheshortrun.

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,whichincludestheopportunitycostofthewagesyouaregivingupbynotworking.Ifthechoiceisbetweenskiingandgoingtothelibrarytostudy,thenthecostofskiingisitsmonetaryandtimecostsincludingthecosttoyouofgettingalowergradeinyourcourse.

4.Ifyouspend$100nowinsteadofsavingitforayearandearning5percentinterest,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.Ronwantstolookataveragecost.ButbothHarryandRonaremissingtheothersideoftheequationrevenue.Afirmwantstomaximizeitsprofits,soitneedstoexaminebothcostsandrevenues.Thus,Hermioneisrightit’sbesttoexaminewhethertheextrarevenuewouldexceedtheextracosts.Hermioneistheonlyonewhoisthinkingatthemargin.

7.a.TheprovisionofSocialSecuritybenefitslowersanindividual’sincentivetosaveforretirement.Thebenefitsprovidesomelevelofincometotheindividualwhenheorsheretires.Thismeansthattheindividualisnotentirelydependentonsavingstosupportconsumptionthroughtheyearsinretirement.

b.Sinceapersongetsfewerafter-taxSocialSecuritybenefitsthegreaterishisorherearnings,thereisanincentivenottowork（ornotworkasmuch）