克鲁格曼国际经济学答案(1)

1Chapter21．Homehas1200unitsoflaboravailable.Itcanproducetwogoods,applesandbananas.Theunitlaborrequirementinappleproductionis3,whileinbananaproductionitis2.a．Graphouttheproductionpossibilitiesfrontier:b．Whatistheopportunitycostofapplesintermsofbananas?5.1LbLaaac．Intheabsenceoftrade,whatwouldthepriceofapplesintermsofbananasbe?Intheabsenceoftrade,sincelaboristheonlyfactorofproductionandsupplydecisionsaredeterminedbytheattemptsofindividualstomaximizetheirearningsinacompetitiveeconomy,onlywhenLbLaba/aa/PPwillbothgoodsbeproduced.So1.5/PPba2．Homeisasdescribedinproblem1.Thereisnowalsoanothercountry,Foreign,withalaborforceof800.Foreign’sunitlaborrequirementinappleproductionis5,whileinbananaproductionitis1.a．GraphForeign’sproductionpossibilitiesfrontier:b．Constructtheworldrelativesupplycurve.Home'sPPF0200400600800200400600800QappleQbananaForeign'sPPF0200400600800100080160240320400Q*appleQ*banana23．Nowsupposeworldrelativedemandtakesthefollowingform:Demandforapples/demandforbananas=priceofbananas/priceofapples.a．Graphtherelativedemandcurvealongwiththerelativesupplycurve:abba/PP/DD∵Whenthemarketachievesitsequilibrium,wehave1ba)(DDbabbaaPPQQQQ∴RDisahyperbolaxy1b．Whatistheequilibriumrelativepriceofapples?TheequilibriumrelativepriceofapplesisdeterminedbytheintersectionoftheRDandRScurves.RD:yx1RS:5]5,5.1[5.1],5.0(5.0)5.0,0[yyyxxx∴25.0yx3∴2/bPaPeec．Describethepatternoftrade.∵babeaebaPPPPPP///∴Inthistwo-countryworld,Homewillspecializeintheappleproduction,exportapplesandimportbananas.Foreignwillspecializeinthebananaproduction,exportbananasandimportapples.d．ShowthatbothHomeandForeigngainfromtrade.InternationaltradeallowsHomeandForeigntoconsumeanywherewithinthecoloredlines,whichlieoutsidethecountries’productionpossibilityfrontiers.Andtheindirectmethod,specializinginproducingonlyoneproductionthentradewithothercountry,isamoreefficientmethodthandirectproduction.Intheabsenceoftrade,Homecouldgainthreebananasbyforegoingtwoapples,andForeigncouldgainbyoneforegoingfivebananas.Tradeallowseachcountrytotradetwobananasforoneapple.HomecouldthengainfourbananasbyforegoingtwoappleswhileForeigncouldgainoneapplebyforegoingonlytwobananas.SobothHomeandForeigngainfromtrade.4．Supposethatinsteadof1200workers,Homehad2400.Findtheequilibriumrelativeprice.WhatcanyousayabouttheefficiencyofworldproductionandthedivisionofthegainsfromtradebetweenHomeandForeigninthiscase?RD:yx1RS:5]5,5.1[5.1],1(1)1,0[yyyxxx∴5.132yx∴5.1/bPaPee4Inthiscase,Foreignwillspecializeinthebananaproduction,exportbananasandimportapples.ButHomewillproducebananasandapplesatthesametime.AndtheopportunitycostofbananasintermsofapplesforHomeremainsthesame.SoHomeneithergainsnorlosesbutForeigngainsfromtrade.5．SupposethatHomehas2400workers,buttheyareonlyhalfasproductioninbothindustriesaswehavebeenassuming,Constructtheworldrelativesupplycurveanddeterminetheequilibriumrelativeprice.Howdothegainsfromtradecomparewiththoseinthecasedescribedinproblem4?Inthiscase,thelaborisdoubledwhiletheproductivityoflaborishalved,sothe＂effectivelabor＂remainsthesame.Sotheanswerissimilartothatin3.AndbothHomeandForeigncangainfromtrade.ButForeigngainslessercomparewiththatinthecase4.