商务统计学智慧树知到期末考试答案章节答案2024年上海大学

商务统计学智慧树知到期末考试答案+章节答案2024年上海大学Asampleof51elementsisselectedtoestimatea95%confidenceintervalforthevarianceofthepopulation.Thechi-squarevaluestobeusedforthisintervalestimationare

答案:32.357and71.420Asampleofsizenisselectedatrandomfromaninfinitepopulation.Asnincreases,whichofthefollowingstatementsistrue?

答案:Thestandarderrorofthesamplemeandecreases.Giventhatthesumofsquaresforerroris60andthesumofsquaresforregressionis140,thecoefficientofdeterminationis:

答案:0.700.Inthesimplelinearregressionmodel,they-interceptrepresentsthe:

答案:valueofywhenx=0.Anormallydistributedpopulationwith200elementshasameanof60andastandarddeviationof10.Theprobabilitythatthemeanofasampleof25elementstakenfromthispopulationwillbesmallerthan56is:

答案:0.0166.ThePearsoncoefficientofcorrelationrequals1whenthereis/areno:

答案:unexplainedvariation.AresearcherhasatheorythatthemeanforpopulationAislessthanthemeanforpopulationB.Totestthis,sherandomlysamples36itemsfrompopulationAanddeterminesthatthesampleaverageis38.4.Sherandomlysamples64itemsfrompopulationBanddeterminesthatthesampleaverageis44.3.ThepopulationvarianceforAis72andthepopulationvarianceforBis48.0.Alphais.05.Theobservedz-valueis_______.

答案:–3.56Whentestingforthedifferencebetweentwopopulationvarianceswithsamplesizesofn1=8andn2=10,thenumberofdegreesoffreedomare:

答案:7,9Ifacoinistossedthreetimes,andastatisticianpredictsthattheprobabilityofobtainingthreeheadsinarowis0.125,whichofthefollowingassumptionsisirrelevanttohisprediction?

答案:Theeventsaredependent.Theaveragescoreforaclassof30studentswas75.The20malestudentsintheclassaveraged70.Thefemalestudentsintheclassaveraged:

答案:85.Whendevelopinganintervalestimateforthedifferencebetweentwosamplemeans,withsamplesizesofn1andn2,

答案:n1andn2canbeofdifferentsizes,A98%confidenceintervalestimateforapopulationmeanisdeterminedtobe75.38to86.52.Iftheconfidencelevelisreducedto90%,theconfidenceinterval:

答案:becomesnarrower.Thosemethodsinvolvingthecollection,presentation,andcharacterizationofasetofdatainordertoproperlydescribethevariousfeaturesofthatsetofdataarecalled:

答案:descriptivestatistics.Themostappropriatetypeofchartfordeterminingthenumberofobservationsatorbelowaspecificvalueis:

答案:acumulativefrequencyogive.Generallyspeaking,iftwovariablesareunrelated(asoneincreases,theothershowsnopattern),thecovariancewillbe:

答案:apositiveornegativenumberclosetozero.Thetotalareaofthebarsinarelativefrequencyhistogram:

答案:dependsonthewidthofeachbar.Thestandardisedresidualisdefinedas:

答案:residualdividedbythestandarderrorofestimate.AbinomialdistributionforwhichthenumberoftrialsnislargecanwellbeapproximatedbyaPoissondistributionwhentheprobabilityofsuccess,p,is:

答案:smallerthan0.05.Supposethatwerejectanullhypothesisatthe0.05levelofsignificance.Forwhichofthefollowinga-valuesdowealsorejectthenullhypothesis?

答案:0.06.Anexperimentconsistsofthreestages.Therearetwopossibleoutcomesinthefirststage,threepossibleoutcomesinthesecondstage,andfourpossibleoutcomesinthethirdstage.Drawingatreediagramforthisexperimentwillshowthatthetotalnumberofoutcomesis:

答案:24.Inregressionanalysis,ifthecoefficientofdeterminationis1.0,then:

答案:thesumofsquaresforerrormustbe0.0.Inasetofnumericaldata,thevalueforQ3canneverbesmallerthanthevalueforQ1.

答案:对Ajointeventisaneventthathastwoormorecharacteristics.

答案:对Ifyouarecomparingtheaveragesalesamongthreedifferentbrands,youaredealingwithathree-wayANOVAdesign.

答案:错Themeanandstandarddeviationofanormallydistributedrandomvariablethathasbeenstandardisedareoneandzero,respectively.

答案:错Anunbiasedestimatorofapopulationparameterisanestimatorwhosestandarddeviationisthesameastheactualvalueofthepopulationstandarddeviation.

答案:错Inthenormaldistribution,thetotalareaunderthecurveisequaltoone.

答案:对Asummarymeasurethatiscomputedfromasampletodescribeacharacteristicofthepopulationiscalledastatistic.

答案:对Thecentrallimittheoremisbasictotheconceptofstatisticalinference,becauseitpermitsustodrawconclusionsaboutthepopulationbasedstrictlyonsampledata,andwithouthavinganyknowledgeaboutthedistributionoftheunderlyingpopulation.

答案:对Ifthevalueofthesumofsquaresforerror,SSE,equalszero,thenthecoefficientofdeterminationmustequalzero.

答案:错Iftwoequallylikelyevents(AandB)aremutuallyexclusiveandcollectivelyexhaustive,theprobabilitythateventAoccursis0.5.

答案:对Usingthestandardnormalcurve,thez-scorerepresentingthe10thpercentileis1.28.

答案:错Foranormalcurve,ifthemeanis25minutesandthestandarddeviationis5minutes,theareatotheleftof10minutesisabout0.50.

答案:错Anunbiasedestimatorisasamplestatistic,whichhasanexpectedvalueequaltothevalueofthepopulationparameter.

答案:对Thecorrelationcoefficientmeasuresonlythestrengthofalinearrelationshipbutnotanycause-and-effect.

答案:对Whichofthefollowingstatementsisnottrue?

答案:Inthelanguageofstatistics,thetermpopulationreferstoagroupofpeopleThewidthofaconfidenceintervalestimateofthepopulationmeanwidenswhenthe:

答案:Alltheoptionsarecorrect

.Independentsimplerandomsamplesaretakentotestthedifferencebetweenthemeansoftwopopulationswhosestandarddeviationsarenotknown.Thesamplesizesaren1=25andn2=35.Thecorrectdistributiontouseisthe

答案:tdistributionwith58degreesoffreedomThetwographicaltechniquesweusuallyusetopresentnominal(categorical)dataare:

答案:barchartandpiechart.Therelationshipbetweentwonumerical(quantitative)variablesisgraphicallydisplayedasa:

答案:scatterdiagram.Thebesttypeofchartforcomparingtwosetsofcategoricaldatais:

答案:abarchart.Thestatisticalmethodsofanalysisofvarianceassume______________.

答案:equalpopulationvariancesIftwoindependentlargesamplesaretakenfromtwopopulations,thesamplingdistributionofthedifferencebetweenthetwosamplemeans

答案:canbeapproximatedbyanormaldistributionIfyourollanunbiaseddie50times,youshouldexpectanevennumbertoappear:

答案:25outofthe50rolls,onaverage.Asampleofsize200istobetakenatrandomfromaninfinitepopulation.Giventhatthepopulationproportionis0.60,theprobabilitythatthesampleproportionwillbegreaterthanthe0.58is:

答案:0.719.Apoliticianwhoisrunningfortheofficeofpremierinastatewith3millionregisteredvoterscommissionsasurvey.Inthesurvey,53.6%ofthe5000registeredvotersinterviewedsaytheyplantovoteforhim.Thepopulationofinterestisthe:

答案:3millionregisteredvotersinthestate.Inahistogram,theproportionofthetotalareathatmustbetotheleftofthemedianis:

答案:exactly0.50.Thestatisticaldistributionusedfortestingthedifferencebetweentwopopulationvariancesisthe___distribution.

答案:FTestingwhethertheslopeofthepopulationregressionlinecouldbezeroisequivalenttotestingwhetherthe:

答案:populationcoefficientofcorrelationcouldbezero.Whichofthefollowingisnotacharacteristicofabinomialexperiment?

答案:Eachtrialresultsintwoormoreoutcomes.Therandomvariableforachi-squaredistributionmayassume

答案:anyvaluegreaterthanzeroArandomsampleof400itemsfromapopulationshowsthat160ofthesampleitemspossessagivencharacteristic.Arandomsampleof400itemsfromasecondpopulationresultedin110ofthesampleitemspossessingthecharacteristic.Usingthisdata,a99%confidenceintervalisconstructedtoestimatethedifferenceinpopulationproportionswhichpossessthegivencharacteristic.Theresultingconfidenceintervalis_______.

答案:0.04to0.21IfP(A)=0.20,P(B)=0.30andP(A∩B)=0.06,thenAandBare:

答案:independentevents.Intestingforthedifferencesbetweenthemeansoftwoindependentpopulationswherethevariancesineachpopulationareunknownbutassumedequal,thedegreesoffreedomare:

答案:n1+n2-2Theinterquartilerangeisfoundbytakingthedifferencebetweenthe1stand3rdquartilesanddividingthatvalueby2.

答案:错Ifthemeanofanumericaldatasetexceedsthemedian,thedataareconsideredtobeleft-skewed.

答案:错Ifallpossiblesamplesofsizenaredrawnfromaninfinitepopulationwithameanof60andastandarddeviationof8,thenthestandarderrorofthesamplemeanequals1.0onlyforsamplesofsize64.

答案:对Forconditionalprobabilities:P(A|B)willalwaysequalP(B|A).

答案:错Anintervalestimateisarangeofvalueswithinwhichtheactualvalueofapopulationparametermayfall.

答案:对Thevaluethatseparatesarejectionregionfromanonrejectionregioniscalledthep-value.

答案:错TheprobabilityofeventAandeventBoccurringmustbeequalto1.

答案:错Statisticalindependencemeanstheoutcomeofoneeventisindependentoftheoutcomeofasecondevent.

答案:对Ifalphaischosentobe5%andthep-valueforthehypothesistestis0.044,thenthenullhypothesisshouldberejected.

答案:对Anothernamefortheresidualterminaregressionequationisrandomerror.

答案:对Arelativefrequencydistributiondescribestheproportionofdatavaluesthatfallwithineachcategory.

答案:对Aone-tailp-valueistwotimesthesizeofthatforatwo-tailtest.

答案:错Nominal(categorical)datamaybetreatedasordinalornumerical(quantitative).

答案:错Asageneralrule,thenormaldistributionisusedtoapproximatethesamplingdistributionofthesampleproportiononlyifthesamplesizenisgreaterthanorequalto30.

答案:错Intestingahypothesis,statementsforthenullandalternativehypotheses,aswellastheselectionofthelevelofsignificance,shouldprecedethecollectionandexaminationofthedata.

答案:对Giventhefollowinginformation:Standarddeviation=8Coefficientofvariation=64%Themeanwouldthenbe

答案:12.5Aweightedaverageofthevalueofarandomvariable,wheretheprobabilityfunctionprovidesweightsisknownas

答案:theexpectedvalueAtheoremthatallowsustousethenormalprobabilitydistributiontoapproximatethesamplingdistributionofsamplemeansandsampleproportionswheneverthesamplesizeislargeisknownasthe

答案:centrallimittheoremFromapopulationof500elements,asampleof225elementsisselected.Itisknownthatthevarianceofthepopulationis900.Thestandarderrorofthemeanisapproximately

答案:1.4847Asampleof400observationswillbetakenfromaninfinitepopulation.Thepopulationproportionequals0.8.Theprobabilitythatthesampleproportionwillbegreaterthan0.83is

答案:0.0668IfAandBareindependentevents,then

答案:P(A)mustbeequaltoP(A│B)Thepurposeofstatisticalinferenceistoprovideinformationaboutthe

答案:populationbaseduponinformationcontainedinthesampleThestudentbodyofalargeuniversityconsistsof60%femalestudents.Arandomsampleof8studentsisselected.Whatistheprobabilitythatamongthestudentsinthesampleexactlytwoarefemale?

答案:0.0413

答案:1.431

答案:0.7Whichofthefollowingtechniquesisusedtopredictthevalueofonevariableonthebasisofothervariables?

答案:Regressionanalysis.GiventhattherandomvariableXisnormallydistributedwithameanof80andastandarddeviationof10,P(85≤X≤90)is:

答案:0.1498.Ifthecoefficientofcorrelationis0.90,thepercentageofthevariationinthedependentvariableythatisexplainedbythevariationintheindependentvariablexis:

答案:81%.Whichofthefollowingstatementsaboutthearithmeticmeanisnotalwayscorrect?

答案:Halfoftheobservationsareoneithersideofthemean.Apointestimateisdefinedas:

答案:asinglevaluethatisthebestestimateofanunknownpopulationparameter.IfXisanormalrandomvariablewithastandarddeviationof10,then3Xhasastandarddeviationequalto:

答案:30.Inatwo-tailtestforthepopulationmean,ifthenullhypothesisisrejectedwhenthealternativehypothesisistrue:

答案:acorrectdecisionismade.Whendataiscollectedinastatisticalstudyforonlyaportionorsubsetofallelementsofinterest,weareusing:

答案:asample.Theproducerofacertainmedicineclaimsthattheirbottlingequipmentisveryaccurateandthatthestandarddeviationofalltheirfilledbottlesis0.1ounceorless.Asampleof20bottlesshowedastandarddeviationof0.11.Theteststatistictotesttheclaimis

答案:22.99Astandardnormaldistributionisanormaldistributionwith:

答案:ameanofzeroandastandarddeviationofone.Asummarymeasurethatiscomputedfromapopulationiscalled:

答案:aparameter.Inwhattypeoftestisthevariableofinterestthedifferencebetweenthevaluesoftheobservationsratherthantheobservationsthemselves?

答案:Atestforthemeandifferencebetweentworelatedpopulations.ThecriticalvalueofFat95%confidencewhenthereisasamplesizeof21forthesamplewiththesmallervariance,andthereisasamplesizeof9forthesamplewiththelargersamplevarianceis

答案:2.45Randomsamplesofsize49aretakenfromaninfinitepopulationwhosemeanis300andstandarddeviationis21.Themeanandstandarderrorofthesamplemean,respectively,are:

答案:300and3.ATypeIerroriscommittedifwemake:

答案:incorrectdecisionwhenthenullhypothesisistrue.Anexperimentconsistsoftossing3unbiasedcoinssimultaneously.Drawingaprobabilitytreeforthisexperimentwillshowthatthenumberofsimpleeventsinthisexperimentis:

答案:nocorrectoptions.Inahistogram,theproportionofthetotalareathatmustbetotherightofthemeanis:

答案:exactly0.50ifthedistributionissymmetricandunimodal.Aregressionlineusing25observationsproducedSSR=118.68andSSE=56.32.Thestandarderrorofestimatewas:

答案:1.5648.APoissondistributionwithµ=.60isa:

答案:positivelyskeweddistribution(skewedtotheright).Tocomputeanintervalestimateforthedifferencebetweenthemeansoftwopopulations,thetdistribution

答案:isnotrestrictedtosmallsamplesituationsIfthecoefficientofdeterminationis0.975,thentheslopeoftheregressionline:

答案:couldbeeitherpositiveornegative.Theempiricalrulestatesthattheapproximatepercentageofmeasurementsinadataset(providedthatthedatasethasabell-shapeddistribution)thatfallwithintwostandarddeviationsoftheirmeanisapproximately:

答案:95%.Asampleof20cansoftomatojuiceshowedastandarddeviationof0.4ounces.A95%confidenceintervalestimateofthevarianceforthepopulationis

答案:0.0925to0.3413Amodalclassistheclassthatincludes:

答案:thelargestnumberofobservations.Supposethemeansquaresfortreatmentinaone-wayANOVAare24.4andthemeansquaresforerrorare9.8.Therewerefourtreatmentsand7subjectsreceivedeachtreatment(foratotalof28).ThecalculatedvalueofFis_______.

答案:2.49Aresearcherisinterestedintestingtodetermineifthemeanofpopulationoneisgreaterthanthemeanofpopulationtwo.Thenullhypothesisisthatthereisnodifferenceinthepopulationmeans(i.e.thedifferenceiszero).Thealternativehypothesisisthatthereisadifference(i.e.thedifferenceisnotequaltozero).Herandomlyselectsasampleof9itemsfrompopulationoneresultinginameanof14.3andastandarddeviationof3.4.Herandomlyselectsasampleof14itemsfrompopulationtworesultinginameanof11.8andastandarddeviation2.9.Heisusinganalphavalueof.10toconductthistest.Assumingthatthepopulationsarenormallydistributed,thecriticalt-valuefromthetableis_______.

答案:1.721IfXandYaretwoindependentrandomvariableswithV(X)=7.5andV(Y)=6,thenV(2X+3Y)is:

答案:84.ThedegreesoffreedomfortheFtestinaone-wayANOVAare:

答案:(c-1)and(n-c).Inananalysisofvarianceprobleminvolving3treatmentsand10observationspertreatment,SSE=399.6.TheMSEforthissituationis

答案:14.8JimandJohngotoacoffeeshopduringtheirlunchbreakandtossacointoseewhowillpay.TheprobabilitythatJohnwillpaythreedaysinarowis0.125.

答案:对Acumulativefrequencydistributionliststhenumberofobservationsthatarewithinorbeloweachoftheclasses.

答案:对ArandomvariableXisnormallydistributedwithameanof150andavarianceof36.GiventhatX=120,itscorrespondingz-scoreis5.0.

答案:错Anunbiasedestimatorissaidtobeconsistentifthedifferencebetweentheestimatorandtheparametergrowssmallerasthesamplesizegrowslarger.

答案:对Themiddlespread,thatis,themiddle50%ofthenormaldistribution,isequalto1standarddeviation.

答案:错Thedegreesoffreedominthecalculationofthepopulationvarianceisn--1.

答案:错Ifwerejectanullhypothesisatthe0.05levelofsignificance,thenwemustalsorejectitatthe0.10level.

答案:对TheMSEmustalwaysbepositiveinatwo-wayANOVAsetting.

答案:对Apopulationwith200elementshasameanof10.Fromthisinformation,itcanbeshownthatthepopulationstandarddeviationis15.

答案:错Asampleof15observationshasastandarddeviationof4.Thesumofthesquareddeviationsfromthesamplemeanis60.

答案:错Thecoefficientofvariationisameasureofrelativedispersion.

答案:对Inapositivelyskeweddistribution,themeanislargerthanthemedianandthemedianislargerthanthemode.

答案:对AlocalcableTVsystemusingasampleof500subscribersestimatesthat40%ofitssubscriberswatchapremiumchannelatleastonceperday.Thisisanexampleofstatisticalinferenceasopposedtodescriptivestatistics.

答案:错Thecoefficientofvariationmeasuresvariabilityinadatasetrelativetothesizeofthemedian.

答案:错GiventhatSSE=60andSSR=540,theproportionofthevariationinythatisexplainedbythevariationinxis0.90.

答案:对Thelargerthelevelofconfidenceusedinconstructingaconfidenceintervalestimateofthepopulationmean,thenarrowertheconfidenceinterval.

答案:错Thecoefficientofvariationallowsustocomparetwosetsofdatabasedondifferentmeasurementunits.

答案:对Ateststatisticisanumericalquantitycomputedfromthedataofasampleandisusedinreachingadecisiononwhetherornottorejectthenullhypothesis.

答案:对Intestingfordifferencesbetweenthemeansoftwoindependentpopulations,thenullhypothesisstatesthat:

答案:thedifferencebetweenthetwopopulationmeansisequalto0.Aninfinitepopulationhasameanof60andastandarddeviationof8.Asampleof50observationsistobetakenatrandomfromthispopulation.Theprobabilitythatthesamplemeanwillbebetween57and62is:

答案:0.9576.Whichofthefourmethodsofdatacollectionisinvolvedwhenapersonretrievesdatafromanonlinedatabase?

答案:publishedsourcesAfteryoucalculatethesamplesizeneededtoestimateapopulationproportiontowithin0.04,yourstatisticslecturertellsyouthemaximumallowableerrormustbereducedtojust0.01.Iftheoriginalcalculationledtoasamplesizeof800,thesamplesizewillnowhavetobe:

答案:12800.Ifthecoefficientofcorrelationbetweenxandyiscloseto1.0,thisindicatesthat:

答案:Theremayormaynotbeanycausalrelationshipbetweenxandy.Whichprobabilitydistributionisappropriatewhentheeventsofinterestoccurrandomly,independentlyofoneanother,andrarely?

答案:Poissondistribution.Toconstructanintervalestimateforthedifferencebetweenthemeansoftwopopulationswhenthestandarddeviationsofthetwopopulationsareunknown,wemustuseatdistributionwith(letn1bethesizeofsample1andn2thesizeofsample2)

答案:(n1+n2-2)degreesoffreedomIfyouaretestingahypothesisthattwopopulationproportionsarethesame,you_______.

答案:shouldcalculatea‘pooled’valueforthesampleproportionGiventhatZisastandardnormalrandomvariable,themeanofZis:

答案:alwaysequaltozero.Theprobabilitydensityfunctionf(x)ofarandomvariableXthatisnormallydistributediscompletelydeterminedoncethe:

答案:meanandvarianceofXarespecified.1.ForsomepositivevalueofX,theprobabilitythatastandardizednormalvariableisbetween0and+1.5Xis0.4332.ThevalueofXis

答案:1.00Thezvaluefora96.6%confidenceintervalestimateis:

答案:2.12.Aresearcherwantstoconductabefore/afterstudyon11subjectstodetermineifatreatmentresultsinanydifferenceinscores.Thenullhypothesisisthattheaveragedifferenceiszerowhilethealternativehypothesisisthattheaveragedifferenceisnotzero.Scoresareobtainedonthesubjectsbothbeforeandafterthetreatment.Aftersubtractingtheafterscoresfromthebeforescores,theaveragedifferenceiscalculatedtobe–2.40withasamplestandarddeviationof1.21.Assumethatthedifferencesarenormallydistributedinthepopulation.Theobservedt-valueforthistestis_______.

答案:–6.58WhichofthefollowingcomponentsinanANOVAtablearenotadditive?

答案:meansquaresIfAandBaremutuallyexclusiveevents,withP(A)=0.20andP(B)=0.30,thenP(A∩B)is:

答案:0.00.TwoeventsAandBaresaidtobeindependentif:

答案:P(A∩B)=P(A)×P(B).Inhypothesistesting,whateverweareinvestigatingorresearchingisspecifiedas:

答案:thealternativehypothesis.Inanalyzingcategoricaldata,thefollowinggraphicaldeviceisNOTappropriate:

答案:stemandleafdisplayIfahypothesisisrejectedatthe0.025levelofsignificance,it:

答案:mayberejectedornotrejectedatthe0.01level.Independentsimplerandomsamplesaretakentotestthedifferencebetweenthemeansoftwopopulationswhosevariancesarenotknown.Thesamplesizesaren1=32andn2=40.Thecorrectdistributiontouseisthe

答案:tdistributionwith70degreesoffreedomAsampleof250observationsistobeselectedatrandomfromaninfinitepopulation.Giventhatthepopulationproportionis0.25,thestandarderrorofthesamplingdistributionofthesampleproportionis:

答案:0.0274.TheSpearmanrankcorrelationcoefficientmustbeusedtodeterminewhetherarelationshipexitsbetweentwovariableswhen:

答案:Alltheoptionsarecorrect

.Theproblemwithrelyingonapointestimateofapopulationparameteristhat:

答案:itdoesnottellushowcloseorfarthepointestimatemightbefromtheparameter.Aresearcherisinterestedintestingtodetermineifthemeanofpopulationoneisgreaterthanthemeanofpopulationtwo.Thenullhypothesisisthatthereisnodifferenceinthepopulationmeans(i.e.thedifferenceiszero).Thealternativehypothesisisthatthereisadifference(i.e.thedifferenceisnotequaltozero).Herandomlyselectsasampleof9itemsfrompopulationoneresultinginameanof14.3andastandarddeviationof3.4.Herandomlyselectsasampleof14itemsfrompopulationtworesultinginameanof11.8andastandarddeviation2.9.Heisusinganalphavalueof.10toconductthistest.Assumingthatthepopulationsarenormallydistributed,thedegreesoffreedomforthisproblemare_______.

答案:21Intestingfordifferencesbetweenthemeansoftworelatedpopulationswherethevarianceofthedifferencesisunknown,thedegreesoffreedomare:

答案:n-1.Inordertoestimatewith95%confidencetheexpectedvalueofyinasimplelinearregressionproblem,arandomsampleof10observationsistaken.Whichofthefollowingt-tablevalueslistedbelowwouldbeused?

答案:2.306.TheStudentt-distributionapproachesthenormaldistributionasthe:

答案:numberofdegreesoffreedomincreases.Arandomsampleof31chargesalesshowedasamplestandarddeviationof$50.A90%confidenceintervalestimateofthepopulationstandarddeviationis

答案:41.39to63.68Wheneachdatavalueinonesampleismatchedwithacorrespondingdatavalueinanothersample,thesamplesareknownas

答案:matchedsamplesIfZisastandardnormalrandomvariable,thenthevaluezforwhichP(-z≤Z≤z)equals0.8764is:

答案:1.54.TamaraHill,FundManagerwithHillcrestValueFund,managesaportfolioof250commonstocks.Tamaraissearchingfora‘lowrisk’issuetoaddtotheportfolio,i.e.onewithapricevariancelessthanthatoftheS&P500index.Moreover,sheassumesanissueisnot‘lowrisk’untildemonstratedotherwise.HerstaffreportedthatduringthelastninequartersthepricevariancefortheS&P500index(population1)was25,andforthelastsevenquartersthepricevarianceforXYCcommon(population2)was8.Assumethatstockpricesarenormallydistributedinthepopulation.Usinga=0.05,theobservedFvalueis_______.

答案:3.13Powell’sPharmacyLtdoperatesaregionalchainof120pharmacies.Eachpharmacy’sfloorplanincludesagreetingcardsectionwhichisrelativelyisolated.SandraRonaki,MarketingManager,feelsthattheleveloflightinginthegreetingcardsectionmayaffectsalesinthisarea.Shechoosesthreelevelsoflighting(soft,mediumandbright)andrandomlyassignssixpharmaciestoeachlightinglevel.InSandra’sexperiment,‘lighting’is_______.

答案:atreatmentvariableWhichofthefollowingstatementsaboutpiechartsisfalse?

答案:Piechartsareusuallyusedtodisplaytherelativesizesofcategoriesfornumerical(quantitative)data.Givenaninfinitepopulationwithameanof75andastandarddeviationof12,theprobabilitythatthemeanofasampleof36observations,takenatrandomfromthispopulation,exceeds78is:

答案:0.0668.Thefunctionf(x)thatdefinestheprobabilitydistributionofacontinuousrandomvariableXisa:

答案:probabilitydensityfunction.Thesamplesizeneededtoestimateapopulationmeantowithin2unitswitha95%confidencewhenthepopulationstandarddeviationequals8is:

答案:62.Randomsamplesofsize81aretakenfromaninfinitepopulationwhosemeanandstandarddeviationare45and9,respectively.Themeanandstandarderrorofthesamplingdistributionofthesamplemeanare:

答案:45and1.IfP(A)=0.84,P(B)=0.76andP(A∪B)=0.90,thenP(A∩B)is:

答案:0.70.Expressedinpercentiles,theinterquartilerangeisthedifferencebetweenthe:

答案:25%and75%values.Themodeistheobservationthatoccursmostfrequently.

答案:对Onecanreducethewidthofaconfidenceintervalbytakingasmallersamplesize.

答案:错Ahistogramissaidtobesymmetricif,whenwedrawaverticallinedownthecenterofthehistogram,thetwosidesareidenticalinshapeandsize.

答案:对AlphaistheprobabilityofaTypeIerror.

答案:对T