宏观经济学课后习题答案Ch 24Aggregate Demand.docx

宏观经济学课后习题答案Ch 24Aggregate Demand.docx

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宏观经济学课后习题答案Ch24AggregateDemand

CHAPTER24

AggregateDemandandAggregateSupplyAnalysis

1.ChapterSummary

2.LearningObjectives

3.ChapterOutline

TeachingTips/TopicsforDiscussion

4.SolvedProblems

5.SolutionstoReviewQuestionsandProblemsandApplications

1.ChapterSummary

Theaggregatedemandandaggregatesupplymodelenablesustoexplainshort-runfluctuationsinrealGDPandthepricelevel.Theaggregatedemandcurve（AD）showstherelationshipbetweenthepricelevelandthequantityofrealGDPdemandedbyhouseholds,firms,andthegovernment.Theshort-runaggregatesupplycurve（SRAS）showstherelationshipintheshortrunbetweenthepricelevelandthequantityofrealGDPsuppliedbyfirms.Thelong-runaggregatesupplycurveshowstherelationshipinthelongrunbetweenthepricelevelandthequantityofrealGDPsupplied.Thefourcomponentsofaggregatedemandareconsumption（C）,investment（I）,governmentpurchases（G）,andnetexports（NX）.Theaggregatedemandcurveisdownwardslopingbecauseadeclineinthepricelevelcausesconsumption,investment,andnetexportstoincrease.Ifthepricelevelchangesbutallelseremainsconstant,theeconomywillmoveupordownastationaryaggregatedemandcurve.Ifanyvariableotherthanthepricelevelchanges,theaggregatedemandcurvewillshift.Thevariablesthatcausetheaggregatedemandcurvetoshiftaredividedintothreecategories:

changesingovernmentpolicies,changesintheexpectationsofhouseholdsandfirms,andchangesinforeignvariables.

Thelong-runaggregatesupplycurveisaverticallinebecause,inthelongrun,realGDPisalwaysatitspotentiallevelandisunaffectedbythepricelevel.Theshort-runaggregatesupplycurveslopesupwardbecauseworkersandfirmsoftenfailtopredictaccuratelythefuturepricelevel.Thethreemainexplanationsofwhythisfailureresultsinanupward-slopingaggregatesupplycurveare:

（1）contractsmakewagesandprices“sticky,”

（2）businessesoftenadjustwagesslowly,and（3）menucostsmakesomepricessticky.Ifthepricelevelchangesbutallelseremainsconstant,theeconomywillmoveupordownastationaryaggregatesupplycurve.Ifanyvariableotherthanthepricelevelchanges,theaggregatesupplycurvewillshift.Theaggregatesupplycurveshiftsasaresultofincreasesinthelaborforceandthecapitalstock,technologicalchange,expectedincreasesordecreasesinthefuturepricelevel,adjustmentsofworkersandfirmstoerrorsinpastexpectationsaboutthepricelevel,andunexpectedincreasesordecreasesinthepriceofanimportantrawmaterial.

Onecanusetheaggregatedemandandaggregatesupplymodeltoillustratethedifferencebetweenshort-runandlong-runmacroeconomicequilibrium.Inlong-runmacroeconomicequilibrium,theaggregatedemandandshort-runaggregatesupplycurvesintersectatapointonthelong-runaggregatesupplycurve.Inshort-runmacroeconomicequilibrium,theaggregatedemandandshort-runaggregatesupplycurvesoftenintersectatapointoffthelong-runaggregatesupplycurve.Anautomaticmechanismdrivestheeconomytolong-runequilibrium.Ifshort-runequilibriumoccursatapointbelowpotentialrealGDP,wagesandpriceswillfallandtheshort-runaggregatesupplycurvewillshifttotherightuntilpotentialGDPisrestored.Ifshort-runequilibriumoccursatapointbeyondpotentialrealGDP,wagesandpriceswillriseandtheshort-runaggregatesupplycurvewillshifttotheleftuntilpotentialGDPisrestored.RealGDPcanbetemporarilyaboveorbelowitspotentiallevel,eitherbecauseofshiftsintheaggregatedemandcurveorbecausesupplyshocksleadtoshiftsintheaggregatesupplycurve.

Tomaketheaggregatedemandandaggregatesupplymodelmorerealistic,weneedtomakeitdynamicbyincorporatingthreefactsthatwereleftoutofthebasicmodel:

（1）PotentialrealGDPincreasescontinually,shiftingthelong-runaggregatesupplycurvetotheright.

（2）Duringmostyears,aggregatedemandwillbeshiftingtotheright.（3）Exceptduringperiodswhenworkersandfirmsexpecthighratesofinflation,theaggregatesupplycurvewillbeshiftingtotheright.Thedynamicaggregatedemandandaggregatesupplymodelallowsustoanalyzemacroeconomicconditions,includingtherecoveryfromthe2001recession.

2.LearningObjectives

Studentsshouldbeableto:

∙Discussthedeterminantsofaggregatedemand,anddistinguishbetweenamovementalongtheaggregatedemandcurveandashiftofthecurve.

∙Discussthedeterminantsofaggregatesupply,anddistinguishbetweenamovementalongtheshort-runaggregatesupplycurveandashiftofthecurve.

∙Usetheaggregatedemandandaggregatesupplymodeltoillustratethedifferencebetweenshort-runandlong-runmacroeconomicequilibrium.

∙Usethedynamicaggregatedemandandaggregatesupplymodeltoanalyzemacroeconomicconditions.

3.ChapterOutline

CaterpillarRecoversSlowlyfromthe2001Recession

1.CaterpillarInc.,aleadingmultinationalcorporation,manufacturesmoreconstructionandminingequipmentthananycompanyintheworld.Caterpillar’ssalesareaffectedbyfactorssuchasexchangerates,tariffs,andchangingattitudesofforeigngovernmentstowardmultinationalcorporations.Duringrecessions,investmentspendingdeclines.Inthefallof2000,evenbeforetherecessionhadformallybegun,Caterpillarexperiencedadeclineinsales.Theslowrecoveryfromthe2001recessionwasnotuniquetoCaterpillar.Themanufacturingsectorasawholerecoveredmoreslowlyfromthe2001recessionthanfromanyotherrecessionsinceWorldWarII.

►Teachingtips:

OnecanusetheaggregatedemandandaggregatesupplymodeltoanalyzewhathappensduringthebusinesscycleandtounderstandwhyCaterpillarandmanyotherU.S.companiesrecoveredsoslowlyfromtherecessionof2001.Therecessionof2001illustratesanimportantpointaboutmacroeconomics.Attheendofthischapter,AnInsideLookdescribestherecoveryoftheJapaneseeconomyanditseffectsonKomatsu,Caterpillar’sJapaneserival.Ithighlightstheeffectofincreasingexportsonaggregatedemand.Thesereadingscanbeusedasthebasisforclassroomdiscussion,homeworkassignmentsorexaminationquestionsregardingthesignificanceofinflationandunemploymentaskeymacroeconomicproblems.

AggregateDemand

1.Inordertounderstandwhathappensduringthebusinesscycle,oneneedstoexplainfluctuationsinrealGDP,theunemploymentrate,andtheinflationrate.

A.Aggregatedemandandaggregatesupplymodelisamodelthatexplainsshort-runfluctuationsinrealGDPandthepricelevel.

B.Aggregatedemandcurve（AD）isacurveshowingtherelationshipbetweenthepricelevelandthequantityofrealGDPdemandedbyhouseholds,firms,andthegovernment.

C.Short-runaggregatesupplycurve（SRAS）isacurveshowingtherelationshipintheshortrunbetweenthepricelevelandthequantityofrealGDPsuppliedbyfirms.

D.Intheshort-run,realGDPandthepricelevelaredeterminedbytheinteractionoftheaggregatedemandcurveandtheshort-runaggregatesupplycurve.

E.TheaggregatedemandcurveisdownwardslopingbecauseafallinthepricelevelincreasesthequantityofrealGDPdemanded.

I.TheWealthEffectexplainshowachangeinthepricelevelaffectsconsumption.

II.TheInterest-RateEffectexplainshowachangeinthepricelevelaffectsinvestment.

III.TheInternational-TradeEffectexplainshowachangeinthepricelevelaffectsnetexports.

F.Threevariablesshifttheaggregatedemandcurve:

I.Changesingovernmentpolicies.

i.Anincreaseininterestratesshiftstheaggregatedemandleftward.

ii.Anincreaseingovernmentpurchasesshiftstheaggregatedemandrightward.

II.Changesintheexpectationsofhouseholdsandfirms.

i.Anincreaseinhouseholds’expectationsoftheirfutureincomesshiftstheaggregatedemandrightward.

ii.Anincreaseinfirms’expectationsofthefutureprofitabilityofinvestmentspendingshiftstheaggregatedemandrightward.

III.Changesinforeignvariables.

i.AnincreaseinthegrowthrateofdomesticGDPrelativetothegrowthrateofforeignGDPshiftstheaggregatedemandcurveleftward.

ii.Anincreaseinthevalueofthedollarrelativetoforeigncurrenciesshiftstheaggregatedemandcurveleftward.

►Teachingtips:

Itwillbeusefulforstudentstogothroughthegraphicalillustrationoftheaggregatedemandcurve.Studentsusuallyconfuseamovementalongtheaggregatedemandcurveandashiftofthecurve.Oneneedstoreinforcethisthroughclassroomdiscussion,useofnumericalexamples,andhomeworkassignments.AssignSolvedProblem12-1andproblem5oftheProblemsandApplicationssectionattheendofthechaptertoreinforcestudents’understandingofthesetopics.UseMakingtheConnection12-1toexplainhowchangesintheexchangeratebetweenthedollarandtheeuroaffectCaterpillar’ssales.ThefallingvalueofthedollaragainsttheeurohelpedincreaseCaterpillar’ssalesfrom2002to2004.

Don’tLetThisHappenToYou!

clarifieswhytheaggregatedemandcurveisdownwardsloping.Assignproblem4oftheProblemsandApplicationssectionattheendofthechaptertoreinforcestudents’understandingofthesetopics.

AggregateSupply

1.Therearetwoaggregatesupplycurves:

onefortheshort-runandoneforthelong-run.

Long-runaggregatesupplycurve（LRAS）isacurveshowingtherelationshipinthelongrunbetweenthepricelevelandthequantityofrealGDPsupplied.

Changesinthepriceleveldonotaffectthelevelofaggregatesupplyinthelong-run.

2.Theshort-runaggregatesupplycurve（SRAS）isupwardslopingfortworeasons:

A.Asthepricelevelincreases,thequantityofgoodsandservicesfirmsarewillingtosup