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CD19-1CHAPTER19INVENTORYMANAGEMENTWITHUNCERTAINDEMANDReviewQuestions19.1-1Freddieshouldconsiderthetrade-offbetweentoomuchinventoryandtoolittleinventory.19.1-2BasedonFreddie’sdata,9,10,and11aretheonlynumbersofcopiesthathehassoldinthepast.19.1-3Thestateofnatureforeachdayisthenumberofrequeststopurchaseacopythatwilloccur.Thenumberofrequestsisthestateofnaturebecauseitistherandomvariable.19.2-1Onlyasingletimeperiodisneededbecauseperishableproductscannotbesoldlater.19.2-2Theonlydecisiontobemadeishowmanyunitstoordersotheycanbeplacedintoinventoryatthebeginningoftheperiod.19.2-3Itisassumedthatthedemandduringtheperiodisuncertainbutthattheprobabilitydistributionofdemandisknown.19.2-4Theunitcostofunderorderingisthedecreaseinprofitthatresultsfromfailingtoorderaunitthatcouldhavebeensoldduringtheperiod.Theunitcostofoverorderingisthedecreaseinprofitthatresultsfromorderingaunitthatcouldnotbesoldduringtheperiod.19.2-5Bayes’decisionrulewillmakethesamedecisionsincebothapproachesareapplyingBayes’decisionrule,butwithdifferentpayoffs,whereoneistobemaximizedandtheotherminimized.19.2-6Theservicelevelistheprobabilitythatnoshortagewilloccur.19.2-7Optimalservicelevel=Cunder/(Cunder+Cover).19.2-8Thepointatwhichtheoptimalservicelevelhitsthecumulativedistributionfunctiongivestheoptimalorderquantity.19.2-9Yes.19.3-1Therehavebeenfourstockoutsofpanoramicdisposablecamerasduringtheyearwithdurationsrangingfromafewdaystoacoupleweeks.19.3-2RecentcomplaintsfromdistributorsaboutdelaysinshippingthedisposablepanoramiccamerahaveconcernedtheVicePresidentforMarketingandsheissuggestinghavingmorefrequentproductionrunstokeeptheinventorybetterstocked.19.3-3TheDivisionVicePresidentforProductionisconcernedaboutthefrequentinterruptionsintheproductionofothermodelscausedbysettingupforaproductionrunforthedisposablepanoramiccameras.Heisrecommendinghavingmuchlongerproductionrunsmuchlessfrequently.CD19-219.3-4TheDivisionPresidentisskepticalabouthisVicePresident’srecommendationbecauseitwouldincreaseinventorylevels.Hehasbeenpromotingthejust-in-timephilosophyofminimizinginventory.19.4-1Themanagementscienceteambeganbytryingtodiagnosewhythefrequentstockoutswereoccurringunderthecurrentinventorypolicy.19.4-2Undertheoldinventorypolicy,theprobabilityofastockoutis50%andthemaximumsizeofastockoutis8,000.19.4-3Reorderpoint=averagesalesduringleadtime+amountofsafetystock.19.4-4Evenwhentheamountofsafetystockprovidedstillpermitsoccasionalshortstockouts,thissafetystockcandramaticallyimprovetheservicetocustomersbygreatlyreducingboththenumberandlengthofthedelaysinfillingcustomerorders.19.4-5Managementmadethedecisiononhowmuchsafetystocktoprovide.19.4-6Therelevantcostfactorsforchoosingtheorderquantityareacquisitioncosts,setupcosts,holdingcosts,andshortagecosts.19.4-7Themaincomponentofshortagecostsislostfutureprofitfromlostfuturesalescausedbycustomerdissatisfactionwithdelaysinfillingcurrentorders.19.4-8Increasingtheorderquantitydecreasestheaveragemonthlysetupcostsbecausethisdecreasestheaveragenumberofsetupsrequiredpermonth.Increasingtheorderquantityincreasestheaveragemonthlyholdingcosts,sincethisincreasestheaverageinventorylevel.Increasingtheorderquantitydecreasestheaveragemonthlyshortagecosts,becausethisdecreasestheaveragenumberofopportunitiesforstockoutpermonth.19.4-9ThemanagementscienceteamusedtheEOQmodelwithplannedshortagestofindtheapproximatelyoptimalorderquantity.19.4-10ThePresidentisunhappyaboutthelargeincreaseininventorylevels.TheVicePresidentforMarketingisconcernedthatshortagesofvariousmagnitudesstillcanbeexpectedtooccuraboutonceperyear.TheVicePresidentforProductionisunhappybecausethepolicywouldonlyslightlydecreasethefrequencyofproductionruns.19.4-11Thehighsetupcost,thelongleadtime,andthehighvariabilityinmonthlysaleswerethethreefactorsthecausedthecostofthisinventorypolicytobeunusuallyhigh.19.4-12Thesetupcostandleadtimewillbegreatlyreducedbyacquiringsomeadditionalproductionfacilitiesthatwouldbeusedsolelyforproductionofthedisposablepanoramiccameras.19.5-1Thecameraisconsideredastableproductbecauseeachcameraininventorywillremainsellableindefinitely.19.5-2Acontinuous-reviewinventorysystemisonewheretheinventorylevelofastableproductismonitoredonacontinuousbasissothatanewordercanbeplacedassoonastheinventoryleveldropstothereorderpoint.CD19-319.5-3Thetraditionalmethodofimplementingacontinuous-reviewinventorysystemwastouseatwo-binsystem.19.5-4Thecommonmodernmethodofimplementingacontinuous-reviewinventorysystemisacomputerizedinventorysystem.19.5-5An(R,Q)inventorypolicycontrolsacontinuous-reviewinventorysystembyusingafixedreorderpointRandafixedorderquantityQ.19.5-6Exceptforthesetupcost,thecostoftheorderisproportionaltotheorderquantityQ.Acertainholdingcostisincurredforeachunitininventoryperunittime.Whenastockoutoccurs,acertainshortagecostisincurredforeachunitbackorderedperunittimeuntilthebackorderisfilled.19.5-7TheEOQmodelwithplannedshortagesisusedtoapproximatetheoptimalorderquantity.19.5-8Thekeydifferencebetweenthemodelsisthatratherthanhavingknowndemandwithafixedrate,themodelinthischapterassu