英文习题练习

Exercises,1.SupposeBart,Benjamin,andBrenteachpurchaseaparticulartypeofelectricpencilsharpeneratapriceof$20.Bartswillingnesstopaywas$22,Benjaminswillingnesstopaywas$25,andBrentswillingnesstopaywas$30.Whichofthefollowingstatementsiscorrect?a.Hadthepriceofthepencilsharpenerbeen$26ratherthan$20,onlyBrentwouldhavebeenabuyer.b.Brentsconsumersurplusisthesmallestofthethreeindividualconsumersurpluses.c.Forthethreeindividualstogether,consumersurplusamountsto$60.d.Thefactthatallthreeindividualspaid$20forthesametypeofpencilsharpenerindicatesthateachoneplacedthesamevalueonthatpencilsharpener.,2.Ifthequantitysuppliedisthesameregardlessofprice,thensupplyisa.elastic.b.perfectlyelastic.c.perfectlyinelastic.d.inelastic.3.Whenthereisashortageof100unitsofaparticulargood,a.thelawofsupplypredicts(预报）upwardpressureonthepriceofthegoodfromitscurrentlevel.b.thelawofdemandpredictsdownwardpressureonthepriceofthegoodfromitscurrentlevel.c.wesaythatthereisascarcityof100unitsofthegood.d.Noneoftheaboveiscorrect.,4.Anincreaseinthenumberofcollegescholarships(奖学金）issuedbyprivatefoundationswoulda.increasethesupplyofeducation.b.decreasethesupplyofeducation.c.increasethedemandforeducation.d.decreasethedemandforeducation.,5.Nationaldefense（国防）ductsprovidedbythegovernmentareproducedmoreefficiently.c.free-ridersmakeitdifficultforprivatemarketstosupplythesociallyoptimalquantity.d.publicgoodsincreasegovernmentrevenues.6.Averagetotalcostisveryhighwhenasmallamountofoutputisproducedbecausea.averagevariablecostishigh.b.averagefixedcostishigh.c.marginalcostishigh.d.marginalproductishigh.,7.Supposeafirminacompetitivemarketreceived$1,000intotalrevenueandhadamarginalrevenueof$10forthelastunitproducedandsold.Whatistheaveragerevenueperunit,andhowmanyunitsweresold?a.$5and50b.$5and100c.$10and50d.$10and100,8.Letthedemandandsupplyforagoodbegivenbyqd=160038pqs=2p+400Whatistheequilibriumquantityandprice?Solution：qd=qs160038p=2p+400Solveit,p=30,qd=qs=2p+400=460So,theequilibriumquantityis460,andtheequilibriumpriceis30.,9.Amonopolisthasaunitproductioncostof$10.Thefirmhasidentifiedtwodistinctgroupsofcustomers.GroupAhasademandcurveofqA=1004pA,whilegroupBhasademandcurveofqB=603pB.(a)Whichgrouppaysthehigherpriceifthemonopolistpricediscriminates?(b)Ifthemonopolistisnotabletopricediscriminate,whatcommonpricedoesitcharge?,Solution:EpA=dqA/dpA=4EpB=dqB/dpB=3So,theEpAisgreaterthanEpB,then,groupBpaysthehigherpriceifthemonopolistpricediscriminates.(b)Thetotaldemandfunctionofthemonopolistisqm=qA+qB=(1004p)+(603p)=160-7p.ThemarginalrevenueisMR=dTR/dp=160-14p;Themarginalcostis$10,For