经济学原理chapter 3.docx

经济学原理chapter 3.docx

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经济学原理chapter3

ProblemsandApplications

1.Inthetextexampleofthefarmerandtherancher,thefarmer’sopportunitycostofproducingonepoundofmeatistwopoundsofpotatoesbecauseforeveryhourofwork,hecanproduceonepoundofmeatortwopoundsofpotatoes.Withlimitedtimeathisdisposal,producingapoundofmeatmeanshegivesuptheopportunitytoproducetwopoundsofpotatoes.Similarly,therancher’sopportunitycostofproducingonepoundofmeatis1/8poundofpotatoesbecauseforeveryhourofwork,shecanproduceonepoundofmeator1/8poundofpotatoes.Withlimitedtimeatherdisposal,producingapoundofmeatmeansshegivesuptheopportunitytoproduce1/8poundofpotatoes.

2.a.SeeFigure3-2.IfMariaspendsallfivehoursstudyingeconomics,shecanread100pages,sothatistheverticalinterceptoftheproductionpossibilitiesfrontier.Ifshespendsallfivehoursstudyingsociology,shecanread250pages,sothatisthehorizontalintercept.Thetimecostsareconstant,sotheproductionpossibilitiesfrontierisastraightline.

Figure3-2

b.IttakesMariatwohourstoread100pagesofsociology.Inthattime,shecouldread40pagesofeconomics.Sotheopportunitycostof100pagesofsociologyis40pagesofeconomics.

3.a.

Workersneededtomake:

OneCar

OneTonofGrain

U.S.

1/4

1/10

Japan

1/4

1/5

b.SeeFigure3-3.With100millionworkersandfourcarsperworker,ifeithereconomyweredevotedcompletelytocars,itcouldmake400millioncars.SinceaU.S.workercanproduce10tonsofgrain,iftheU.S.producedonlygrainitwouldproduce1,000milliontons.SinceaJapaneseworkercanproduce5tonsofgrain,ifJapanproducedonlygrainitwouldproduce500milliontons.Thesearetheinterceptsoftheproductionpossibilitiesfrontiersshowninthefigure.Notethatsincethetradeoffbetweencarsandgrainisconstant,theproductionpossibilitiesfrontierisastraightline.

Figure3-3

c.SinceaU.S.workerproduceseither4carsor10tonsofgrain,theopportunitycostof1caris2½tonsofgrain,whichis10dividedby4.SinceaJapaneseworkerproduceseither4carsor5tonsofgrain,theopportunitycostof1caris

11/4tonsofgrain,whichis5dividedby4.Similarly,theU.S.opportunitycostof1tonofgrainis2/5cars（4dividedby10）andtheJapaneseopportunitycostof1tonofgrainis4/5cars（4dividedby5）.Thisgivesthefollowingtable:

OpportunityCostof:

1Car（intermsoftonsofgraingivenup）

1TonofGrain（intermsofcarsgivenup）

U.S.

21/2

2/5

Japan

11/4

4/5

d.Neithercountryhasanabsoluteadvantageinproducingcars,sincethey’reequallyproductive（thesameoutputperworker）;theU.S.hasanabsoluteadvantageinproducinggrain,sinceit’smoreproductive（greateroutputperworker）.

e.Japanhasacomparativeadvantageinproducingcars,sinceithasaloweropportunitycostintermsofgraingivenup.TheU.S.hasacomparativeadvantageinproducinggrain,sinceithasaloweropportunitycostintermsofcarsgivenup.

f.Withhalftheworkersineachcountryproducingeachofthegoods,theU.S.wouldproduce200millioncars（that’s50millionworkerstimes4carseach）and500milliontonsofgrain（50millionworkerstimes10tonseach）.Japanwouldproduce200millioncars（50millionworkerstimes4carseach）and250milliontonsofgrain（50millionworkerstimes5tonseach）.

g.Fromanysituationwithnotrade,inwhicheachcountryisproducingsomecarsandsomegrain,supposetheU.S.changed1workerfromproducingcarstoproducinggrain.Thatworkerwouldproduce4fewercarsand10additionaltonsofgrain.ThensupposetheU.S.offerstotrade7tonsofgraintoJapanfor4cars.TheU.S.willdothisbecauseitvalues4carsat10tonsofgrain,soitwillbebetteroffifthetradegoesthrough.SupposeJapanchanges1workerfromproducinggraintoproducingcars.Thatworkerwouldproduce4morecarsand5fewertonsofgrain.Japanwilltakethetradebecauseitvalues4carsat5tonsofgrain,soitwillbebetteroff.Withthetradeandthechangeof1workerinboththeU.S.andJapan,eachcountrygetsthesameamountofcarsasbeforeandbothgetadditionaltonsofgrain（3fortheU.S.and2forJapan）.Thusbytradingandchangingtheirproduction,bothcountriesarebetteroff.

4.a.Pat’sopportunitycostofmakingapizzais1/2gallonofrootbeer,sinceshecouldbrew1/2galloninthetime（2hours）ittakeshertomakeapizza.Pathasanabsoluteadvantageinmakingpizzasinceshecanmakeoneintwohours,whileittakesKrisfourhours.Kris’sopportunitycostofmakingapizzais2/3gallonsofrootbeer,sinceshecouldbrew2/3ofagalloninthetime（4hours）ittakeshertomakeapizza.SincePat’sopportunitycostofmakingpizzaislessthanKris’s,Pathasacomparativeadvantageinmakingpizza.

b.SincePathasacomparativeadvantageinmakingpizza,shewillmakepizzaandexchangeitforrootbeerthatKrismakes.

c.Thehighestpriceofpizzaintermsofrootbeerthatwillmakebothroommatesbetteroffis2/3gallonsofrootbeer.Ifthepricewerehigherthanthat,thenKriswouldprefermakingherownpizza（atanopportunitycostof2/3gallonsofrootbeer）ratherthantradingforpizzathatPatmakes.Thelowestpriceofpizzaintermsofrootbeerthatwillmakebothroommatesbetteroffis1/2gallonofrootbeer.Ifthepricewerelowerthanthat,thenPatwouldprefermakingherownrootbeer（shecanmake1/2gallonofrootbeerinsteadofmakingapizza）ratherthantradingforrootbeerthatKrismakes.

5.a.SinceaCanadianworkercanmakeeithertwocarsayearor30bushelsofwheat,theopportunitycostofacaris15bushelsofwheat.Similarly,theopportunitycostofabushelofwheatis1/15ofacar.Theopportunitycostsarethereciprocalsofeachother.

b.SeeFigure3-4.Ifall10millionworkersproducetwocarseach,theyproduceatotalof20millioncars,whichistheverticalinterceptoftheproductionpossibilitiesfrontier.Ifall10millionworkersproduce30bushelsofwheateach,theyproduceatotalof300millionbushels,whichisthehorizontalinterceptoftheproductionpossibilitiesfrontier.Sincethetradeoffbetweencarsandwheatisalwaysthesame,theproductionpossibilitiesfrontierisastraightline.

IfCanadachoosestoconsume10millioncars,itwillneed5millionworkersdevotedtocarproduction.Thatleaves5millionworkerstoproducewheat,whowillproduceatotalof150millionbushels（5millionworkerstimes30bushelsperworker）.ThisisshownaspointAonFigure3-4.

c.IftheUnitedStatesbuys10millioncarsfromCanadaandCanadacontinuestoconsume10millioncars,thenCanadawillneedtoproduceatotalof20millioncars.SoCanadawillbeproducingattheverticalinterceptoftheproductionpossibilitiesfrontier.ButifCanadagets20bushelsofwheatpercar,itwillbeabletoconsume200millionbushelsofwheat,alongwiththe10millioncars.ThisisshownaspointBinthefigure.Canadashouldacceptthedealbecauseitgetsthesamenumberofcarsand50millionmorebushesofwheat.

Figure3-4

6.Thoughtheprofessorcoulddobothwritinganddatacollectionfasterthanthestudent（thatis,hehasanabsoluteadvantageinboth）,histimeislimited.Iftheprofessor’scomparativeadvantageisinwriting,itmakessenseforhimtopayastudenttocollectthedata,sincethat’sthestudent’scomparativeadvantage.

7.a.EnglishworkershaveanabsoluteadvantageoverScottishworkersinproducingscones,sinceEnglishworkersproducemoresconesperhour（50vs.40）.ScottishworkershaveanabsoluteadvantageoverEnglishworkersinproducingsweaters,sinceScottishworkersproducemoresweatersperhour（2vs.1）.Comparativeadvantagerunsthesameway.Englishworkers,whohaveanopportunitycostof1/50sweatersperscone（1sweaterperhourdividedby50sconesperhour）,haveacomparativeadvantageinsconeproductionoverScottishworkers,whohaveanopportunitycostof1/20sweaterperscone（2sweatersperhourdividedby40sconesperhour）.Scottishworkers,whohaveanopportunitycostof20sconespersweater（40sconesperhourdividedby2sweatersperhour）,haveacomparativeadvantageinsweaterproductionoverEnglishworkers,whohaveanopportunitycostof50sconespersweater（50sconesperhourdividedby1sweaterperhour）.

b.IfEnglandandScotlanddecidetotrade,ScotlandwillproducesweatersandtradethemforsconesproducedinEngland.Atradewithapricebetween20and50sconespersweaterwillbenefitbothcountries,asthey’llbegettingthetradedgoodatalowerpricethantheiropportunitycostofproducingthegoodintheirowncountry.

c.EvenifaScottishworkerproducedjustonesweaterperhour,thecountrieswouldstillgainfromtrade,becauseScotlandwouldstillhaveacomparativeadvantageinproducingsweaters.Itsopportunitycostforsweaterswouldbehigherthanbefore（40sconespersweater,insteadof20sconespersweaterbefore）.ButtherearestillgainsfromtradesinceEnglandhasahigheropportunitycost（50sconespersweater）.

8.a.Technologicaladvancelowerstheopportunitycostofproducingmeatforthefarmer.Theopportunitycostofproducingapointofmeatwas2poundsofpotatoes;it’snow1/5poundsofpotatoes.Thusthefarmer’sopportunitycostofproducingpotatoesisnow5poundsofmeat.Sincetherancher’sopportunitycostofproducingpotatoesis8poundsofmeat,thefarmerstillhasacomparativeadvantageinproducingpotatoesandtherancherstillhasacomparativeadvantageinproducingmeat.

b.Nowthefarmerwon’tbewillingtotradeapoundofpotatoesfo