数据、模型与决策(运筹学)课后习题和案例答案8..pdf

数据、模型与决策(运筹学)课后习题和案例答案8..pdf

《数据、模型与决策(运筹学)课后习题和案例答案8..pdf》由会员分享，可在线阅读，更多相关《数据、模型与决策(运筹学)课后习题和案例答案8..pdf（47页珍藏版）》请在冰豆网上搜索。

CHAPTER8PERT/CPMMODELSFORPROJECTMANAGEMENTReviewQuestions8.1-1Thebidisfor$5.4millionwithapenaltyof$300,000ifthedeadlineof47weeksisnotmet.Inaddition,abonusof$150,000willbepaidiftheplantiscompletedwithin40weeks.8.1-2Hehasdecidedtofocusonmeetingthedeadlineof47weeks.8.1-3Animmediatepredecessorisanactivitythatmustbecompletedjustpriortostartingthegivenactivity.Giventheimmediatepredecessorsofanactivity,thisactivitythenbecomestheimmediatesuccessorofeachoftheseimmediatepredecessors.8.1-4

（1）theactivitiesoftheproject;

（2）theimmediatepredecessorsoftheactivities;and（3）theestimateddurationoftheactivities8.2-1

（1）activityinformation;

（2）precedencerelationships;and（3）timeinformation（duration）8.2-2InanAOAnetwork,eachactivityisrepresentedbyanarc,whileinanAONnetwork,eachactivityisrepresentedbyanode.AONnetworksarebeingusedhere.8.2-3ThebarsinaGanttchartshowthescheduledstartandfinishtimesforactivitiesinaproject.8.3-1（a）Apaththroughaprojectnetworkisoneoftheroutesfollowingthearrows（arcs）fromthestartnodetothefinishnode;（b）thelengthofapathisthesumoftheestimateddurationsoftheactivitiesonthepath;（c）thelongestpathiscalledthecriticalpath.8.3-2

（1）Theactualdurationofeachactivitymustbethesameasitsestimatedduration;and

（2）eachactivitymustbeginassoonasallitsimmediatepredecessorsarefinished.8.3-3Theearlieststarttimeofanactivityisequaltothelargestoftheearliestfinishtimesofitsimmediatepredecessors.8.3-4Aforwardpassistheprocessofstartingwiththeinitialactivitiesandworkingforwardintimetowardthefinalactivities.8.3-5Itisalastchanceschedulebecauseanythinglaterwilldelaythecompletionoftheproject.8.3-6Thelatestfinishtimeofanactivityisequaltothesmallestofthelateststarttimesofitsimmediatesuccessors.8.3-7Abackwardpassstartswiththefinalactivitiesandworksbackwardintimetowardtheinitialactivitiesinsteadofstartingwiththeinitialactivities.8.3-8Anydelayalongthecriticalpathwilldelayprojectcompletion.8.3-9

（1）Identifythelongestpaththroughtheprojectnetwork;and

（2）identifytheactivitieswithzeroslack-theyareonthecriticalpath.8.4-1Thethreeestimatesarethemostlikelyestimate,optimisticestimate,andpessimisticestimate.8-18.4-2Theoptimisticandpessimisticestimatesaremeanttolieattheextremesofwhatispossible,whereasthemostlikelyestimateprovidesthehighestpointoftheprobabilitydistribution.8.4-3Itisassumedthatthemeancriticalpathwillturnouttobethelongestpaththroughtheprojectnetwork.8.4-4Itisassumedthatthedurationsoftheactivitiesonthemeancriticalpatharestatisticallyindependent.8.4-5|ip=sumofthemeansofthedurationsfbrtheactivitiesonthemeancriticalpath.8.4-6ap2=sumofthevariancesofthedurationsfortheactivitiesonthemeancriticalpath.8.4-7Itisassumedthattheformoftheprobabilitydistributionofprojectdurationisthenormaldistribution.8.4-8Itisusuallyhigherthanthetrueprobability.8.5-1Usingovertime,hiringadditionallabor,andusingspecialmaterialsorequipmentareallwaysofcrashinganactivity.8.5-2Thetwokeypointsarelabelednormalandcrash.Thenormalpointshowsthetimeandcostoftheactivitywhenitisperformedinthenormalway.Thecrashpointshowsthetimeandcostwhentheactivityisfullycrashed.8.5-3No,onlycrashingactivitiesonthecriticalpathwillreducethedurationoftheproject.8.5-4Crashcostsperweeksavedarebeingexamined.8.5-5Thedecisionstobemadearethestarttimeofeachactivity,thereductioninthedurationofeachactivityduetocrashing,andthefinishtimeoftheproject.8.5-6Anactivitycannotstartuntilitsimmediatepredecessorstartsandthencompletesitsduration.8.5-7Becauseofuncertainty,theplanfbrcrashingtheprojectonlyprovidesa50%chanceofactuallyfinishingwithin40weeks,sotheextracostoftheplanisnotjustified.8.6-1PERT/Costisasystematicproceduretohelpthemanagerplan,schedule,andcontrolprojectcosts.8.6-2Itbeginsbydevelopinganestimateofthecostofeachactivitywhenitisperformedintheplannedway.8.6-3Acommonassumptionisthatthecostsofperforminganactivityareincurredataconstantratethroughoutitsduration.8.6-4Aworkpackageisagroupofrelatedactivities.8.6-5PERT/Costusesearlieststarttimeandlateststarttimeschedulesasabasisfordevelopingcostschedules.8.6-6APERT/Costscheduleofcostsshowstheweeklyprojectcostandcumulativeprojectcostforeachtimeperiod.8.6-7APERT/Costreportshowsthebudgetedvalueoftheworkcompletedofeachactivityandthecostoverrunstodate.8-28.6-8Sincedeviationsfromtheplannedworkschedulemayoccur,aPERT/Costreportisneededtoevaluatethecostperformanceofindividualactivities.8.7-1Planning,scheduling,dealingwithuncertainty,time-costtrade-offs,andcontrollingcostsareaddressedbyPERT/CPM.8.7-2Computerimplementationhasallowedfbrapplicationtolargerprojects,fasterrevisionsinprojectplansandeffortlessupdatesandchangesinschedules.8.7-3Theaccuracyandreliabilityofend-pointestimatesarenotasgoodforpointsthatarenotattheextremesoftheprobabilitydistribution.8.7-4ThetechniqueofcomputersimulationtoapproximatetheprobabilitythattheprojectwillmeetitsdeadlineisanalternativefbrimprovingonPERT/CPM.8.7-5ThePrecedenceDiagrammingMethodhasbeendevelopedasanextensionofPERT/CPMtodealwithoverlappingactivities.8.7-6PERT/CPMassumesthateachactivityhasavailablealltheresourcesneededtoperformtheactivityinanormalway.8.7-7Itencourageseffectiveinteractionbetweentheprojectmanagerandsubordinatesthatleadstosettingmutualgoalsfortheproject.8.7-8Newimprovementsandextensionsarestillbeingdevelopedbuthavenotbeenincorporatedmuchintopracticeyet.8-3Problems8.1a）b）Start-AfCFinishStartfAfDfEFinishStartBfCfFinishStartBD-EFinishLength=4weeksLength=7weeksLength=5weeksLength=8weeks*criticalpathc）ActivityESEFLSLFSlackCriticalPathStart00000YesA02131NoB03030YesC35683NoD35350YesE58580YesFinish88880YesCriticalPath:

StartfBDEfFinishd）No,thiswillnotshortenthelengthoftheprojectbecausetheactivityisnotonthecriticalpath.8-48.2a）b）StartfADFinishStart-A-E-FinishStartAfFKfFinisStartfG-HfIfJfFinishStart-B-DFinishStart-B-CEFinishStartBCfH1JFinishStartBCfKFinishLength=4weeksLength=5weeksLength=8weeksLength=8weeksLength=3weeksLength=6weeksLength=8weeksLength=7weeks*criticalpathcriticalpathcriticalpath8-5C）ActivityESEFLSLFSlackCriticalPathStart00000YesA02020YesB01010YesC13130YesD24684NoE36582NoF24240YesG23230YesH34340YesI45450YesJ58580YesK48480YesFinish88880YesCriticalPaths:

StartA-F-KFinishStartAGHIJTFinishStart-BCH1J-Finishd）No,thiswillnotshortenthelengthoftheprojectbecauseAisnotonallofthecriticalpaths.8-68.3a）8-7b,c,&d）ActivityESEFLSLFSlackCriticalPathStart00000YesA01010YesB13130YesC37370YesD36360YesE35461NoF7107100YesG6116110YesH101110110YesI111511150YesJ151715170YesK151816191NoL172017200YesM182319241NoN202420240YesFinish242424240YesCriticalPaths:

StartAfB-CFfHIfJ-LNFinishStart-AB-DG-IJ-LNFinish8-88.4a）b）StartABfJ-LFinishStartCFinishStartfEfFJ-L-FinishStartGJLFinishStartKfLFinishLength=75minutesLength=45minutesLength=72minutesLength=67minutesLength=45minutes*criticalpath8-9CriticalPath:

Start-ABFinishd&e）ActivityESEFLSLFSlackCriticalPathStart00000YesA0300300YesB303530350YesC02303230NoD2532353（）NoE073103NoF73210353NoG0158238NoH152523338NoI252733358NoJ354535450YesK01530453（）NoL457545750YesFinish757575750Yesf）Dinnerwillbedelayed3minutesbecauseofthephonecall.Ifthefoodprocessorisusedthendinnerwillnotbedelayedbecausetherewas3minutesofslackand5minutesofcuttingtimesavedandthecallonlyused6minutesofthe8total.8.5a）StartAfD-HMFinishStartfJ-MFinishStartCF-KfNFinishStartfAfIMfFinishStartfCGfL-NFinishLength=19weeksLength=20weeks*criticalpathLength=16weeksLength=17weeksLength=20weekscriticalpath8-10b）ActivityESEFLSLFSlackCriticalPathStart00000YesA06171NoB03030YesC04040YesD6107111NoE3103100YesF488124NoG4104100YesH101311141NoI6119143NoJ1（）1410140YesK81112154NoL101510150YesM142014200YesN152015200YesFinish202020200YesKenwillbeabletomeethisdeadlineifnodelaysoccur.c）CriticalPaths:

StartfBEJMFinishStartfCGfL-N-FinishFocusattentiononactivitieswith0slack（thoseinthecriticalpaths）.d）IfactivityItakes2extraweekstherewillbenodelaybecauseitsslackis3.IfactivityHtakes2extraweeksthentherewillbeadelayof1weekbecauseitsslackis1.IfactivityJtakes2extraweekstherewillbeadelayof2weeksbecauseithasnoslack.8-118.6a）b）ActivityESEFLSLFSlackCriticalPathStart00000YesA05050YesB01111211NoC13121411NoD597112NoE5115110YesF111411140YesFinish141414140YesCriticalPath:

StartAfE-FFinishLength=14monthsc）6months8-128.7ActivityESEFLSLFSlackCriticalPathStart00000YesA03030YesB3113110YesC112911290YesD293929390YesE293430351NoF344435451NoG3950395（）0YesH506750670YesI293836457NoJ445345541NoK535757614NoL536054611NoM677067700YesN606961701NoFinish70707（）7（）0YesCriticalPath:

StartfAfBCfD-GfHfMFinishTotalduration=70weeks8.8ActivityESEFLSLFSlackCriticalPathStart00000YesA01010YesB13130Yesc39390YesD91311152NoE91（）91（）0YesF1（）1410140YesG131815202NoH182320252NoI91211142NoJ141714170YesK172117210YesL171820213NoM232425262NoN212621260YesFinish262626260YesCriticalPath:

StartA-BC-EKNfFinishTotalduration=26weeks8-138.9Totalduration=28weeksActivityESEFLSLFSlackCriticalPathStart00000YesA01010YesB13130YesC31（）31（）0YesD101413173NoE1