雨课堂学堂在线学堂云《概率论与数理统计(华北电力)》单元测试考核答案

第1题Fourcardsarechosenfromastandarddeckof52playingcardswithreplacement.

Whatistheprobabilityofchoosing4heartsinarow?()A13/52B1/16C1/256DNoneoftheabove第2题Findtheindicatedprobability.Abagcontains6redmarbles,3bluemarbles,and7greenmarbles.Ifamarbleisrandomlyselectedfromthebag,whatistheprobabilitythatitisblue?

()A1/3B1/7C3/16D1/13第3题Astudyconductedatsomeuniversityshowsthat64%oftheschool'sgraduatesfindajobintheirchosenfieldwithinayearaftergraduation.Findtheprobabilitythatamong6randomlyselectedgraduates,atleastonefindsajobinhisorherchosenfieldwithinayearofgraduating.

()A0.167B0.931C0.640D0.998第4题TwoeventsAandBare____iftheoccurrenceornon-occurrenceofoneeventhasnoeffectontheprobabilityoftheoccurrenceornon-occurrenceoftheotherevent.AdependentBdisjointCindependentDnoneofabove第5题TrueorFalse:Thepurposeofanexperimentaffectsthechoiceofsamplespace.(

)第6题TrueorFalse:Randomexperimentsinvolvingthesameexperimentalproceduremayhavedifferentsamplespaces.(

)第7题TrueorFalse:Theprobabilityofaneventisalwayslessthanorequaltoone.(

)第8题TrueorFalse:Theprobabilitiescanbenegativeorgreaterthanone.(

)第9题TrueorFalse:Theimpossibleornulleventϕ,whichcontainsnooutcomesandhenceneveroccurs.(

)第10题TrueorFalse:Thezeroprobabilityeventistheimpossibleevent.()第11题TrueorFalse:ThecertaineventSconsistsofalloutcomesandhencealwaysoccurs.(

)第12题TrueorFalse:Theprobabilityoftheunionoftwoeventsisnogreaterthanthesumoftheindividualeventprobabilities.()第13题TrueorFalse:Ifoutcomesareequallylikely,thentheprobabilityofaneventisequaltothenumberofoutcomesintheeventdividedbythetotalnumberofoutcomesinthesamplespace.(

)第14题TrueorFalse:IfknowledgeoftheoccurrenceofaneventBdoesnotaltertheprobabilityofsomeothereventA,thenitwouldbenaturaltosaythateventAisindependentofB.(

)第15题TrueorFalse:FortwoeventsAandB,supposeP(A)=0.1,P(B)=0.8,andP(A|B)=0.1.ThenAandBareindependent.()第16题TrueorFalse:Mutuallyexclusiveeventsarealwaysindependent.()第17题TrueorFalse:Ingeneraliftwoeventshavenonzeroprobabilityandaremutuallyexclusive,thentheycannotbeindependent.(

)第18题Findtheprobability____-Roundtothenearestthousandth-thatof30randomlyselectedstudentsinourclass,atleasttwosharethesamebirthday.正确答案：:0.706第19题SupposethatEandFaretwoeventsandthatP{EandF}=0.38andP{E}=0.8.ThenP{F|E}=____.正确答案：:0.475第20题SupposethatEandFaretwoeventsandthatP{E}=0.2andP{F|E}=0.5.ThenP{EandF}=____.正确答案：:0.1第21题LetAandB

beeventssuchthat,,and.Thentheprobability=____/12and=____/12.正确答案：:11正确答案：:5第1题Whichoneofthesevariablesisacontinuousrandomvariable?()AThetimeittakesarandomlyselectedstudenttocompleteanexam.BThenumberoftattoosarandomlyselectedpersonhas.CThenumberofwomentallerthan68inchesinarandomsampleof5women.DThenumberofcorrectguessesonamultiplechoicetest.第2题Whichoneofthese‘X’variablesisadiscreterandomvariable?()

AAnexperimentinchemistryisrepeatedmanytimesandXisthetimerequiredforareactiontooccurinseconds.BAstudentisrandomlyselectedandXisthenumberofcorrectanswersonatwoquestionmultiple-choicequiz.CAUPSpackageisrandomlyselectedandXistheweightinpoundsofthepackage.DAstudentisrandomlyselectedandXisthedistancetheymusttravelinfeettogofromtheirdormroomdoortothedooroftheirfirstclassonMondaymorning.第3题Whichofthefollowingisanexampleofabinomialrandomvariable?()AThenumberofgamesyourfavoritebaseballteamwillwinthiscomingseason.BThenumberofquestionsyouwouldgetcorrectonamultiple-choicetestifyourandomlyguessedonallquestions.CThenumberofsiblingsarandomlyselectedstudenthas.DThenumberofcoinsarandomlyselectedstudentiscarrying.第4题Whichoneofthesevariablesisabinomialrandomvariable?（）ATimeittakesarandomlyselectedstudenttocompleteamultiplechoiceexam.BNumberoftextbooksarandomlyselectedstudentboughtthisterm.CNumberofwomentallerthan68inchesinarandomsampleof5women.DNumberofCDsarandomlyselectedpersonowns.第5题Supposethatastudentneedstobuy6booksforhisEnglishcourse.ThenumberofbooksthathewillbeabletofindusedisabinomialrandomvariableXwithn=6andp=0.30.

Inotherwords,theprobabilitythathewillfindanygivenbookusedis0.30,andisindependentfromonebooktothenext.Whatistheprobabilitythathewillfindexactly3usedbooks?()A0.060B0.185C0.324D0.900第6题Thetimetakentoansweranexamquestionforarandomlychosenstudenthasauniformprobabilitydistributionfrom1minuteto5minutes.Whatistheprobabilitythatthetimetoanswerisnomorethan2minutes?（）A0.20B0.25C0.40D0.75第7题Assumethattheweightlossforthefirstmonthofadietprogramvariesbetween6poundsand12pounds,andisspreadevenlyovertherangeofpossibilities,sothatthereisauniformdistribution.Findtheprobabilityofthegivenrangeofpoundslostlessthan10pounds.()ABCD第8题Thetimetakentodeliverabirthdaycakehasauniformprobabilitydistributionfrom20minutesto60minutes.Whatistheprobabilitythatthetimetodeliverabirthdaycakeisatleast25minutes?（）A0.125B0.300C0.700D0.875第9题FindtherequestedprobabilityforthestandardnormalrandomvariableZ.WhatistheprobabilitythatZislessthanorequalto2,P(Z≤2)?（）A0.0228B0.2000C0.5000D0.9772第10题FindtherequestedprobabilityforthestandardnormalrandomvariableZ.

WhatistheprobabilitythatZisbetween-1and1,P(-1≤Z≤1)?（）A0.1587B0.3174C0.6826D0.8413第11题TrueorFalse:Arandomvariableisdefinedasafunctionthatassignsanumericalvaluetotheoutcomeoftheexperiment.()第12题TrueorFalse:AdiscreterandomvariableXisdefinedasarandomvariablethatassumesvaluesfromafinitecountableset.

(

)第13题TrueorFalse:Arandomvariableisdiscreteifitassumesvaluesfromsomecountableset.(

)第14题TrueorFalse:Theprobabilitymassfunctionissufficienttocalculatetheprobabilityofalleventsinvolvingadiscreterandomvariable.()

第15题TrueorFalse:Theprobabilitiesofeventsinvolvingarandomvariablecanbeexpressedasintegralsofitsprobabilitydensityfunction.()第16题TrueorFalse:ThecumulativedistributionfunctionF(x)istheprobabilitythatXfallsintheinterval(-∞tox].(

)第17题TrueorFalse:Ingeneral,thecdfisanondecreasingfunctionthatgrowsfrom0to1asxincreasesfrom-∞to+∞.(

)第18题TrueorFalse:ThecdfF(x)iscontinuousbothfromtherightandfromtheleftforallx.(

)第19题TrueorFalse:Ifiscontinuousat,thenwehave.(

)第20题TrueorFalse:

TheprobabilityofeventsinvolvingacontinuousrandomvariableXcanbeexpressedasintegralsoftheprobabilitydensityfunction.()第21题TrueorFalse:Foranyrealnumbera,wehave.(

)第22题TrueorFalse:foranyrealnumbers.(

)第23题TrueorFalse:Supposethatacoinwithprobabilityofheadsp=0.4isthrown5times.LetXdenotethenumberofheads,thenthedistributionofXisb(5,p).()第24题TrueorFalse:Theuniformrandomvariablearisesinsituationswhereallvaluesinanintervalofthereallineareequallylikelytooccur.()第25题TrueorFalse:LetXbeanexponentialrandomvariablewithparameterthenforany,.()第26题TrueorFalse:If,then.()第27题TrueorFalse:IfXisarandomvariable,thenY=g(X)isalsoarandomvariable,wheregisacontinuousfunction.()第28题Alldiscreteprobabilitymassfunctionsmusthavetheproperties:,and____.正确答案：:1第29题Inordertobealegitemate

pdf,shouldalwaysbenonnegativeand____.正确答案：:1Quiz3第1题TrueorFalse:ThejointpmfofXprovidestheinformationaboutthejointbehaviorofXandY.(

)第2题TrueorFalse:ThejointcdfoftworandomvariablesXandYisF(x,y)=P(X≤xandY≤y).(

)第3题TrueorFalse:Foranytworv’sXandY,thejointcdfisanon-decreasingfunctionabouteveryvariablexandy.()第4题TrueorFalse:Foranytworv’sXandY,thejointcdfsatisfies(

)第5题TrueorFalse:

Foranytworv’sXandY,thejointcdfisrightcontinuousfunctionabouteveryvariablexandy.()第6题TrueorFalse:Themarginalpmf'ssatisfyallthepropertiesofone-dimensionalpmf's.

(

)第7题TrueorFalse:Ingeneral,knowledgeofthemarginalpmf'sissufficienttospecifythejointpmf.(

)第8题TrueorFalse:Ingeneral,themarginalprobabilitydistributionofXcanbedeterminedfromthejointprobabilitydistributionofXandotherrv's.(

)第9题TrueorFalse:TherandomvariablesXandYarejointlycontinuousiftheprobabilitiesofeventsinvolving(X,Y)canbeexpressedasanintegralofaprobabilitydensityfunction.()第10题TrueorFalse:Foranytworv’sXandY,thejointpdf(

)第11题TrueorFalse:Foranytworv’sXandY,thejointpdfsatisfies(

)第12题TrueorFalse:If

f(x,y)isthejointpdfanfF(x,y)thejointcdfofXandY,then.(

)下载视频

第13题TrueorFalse:rvXandYareindependentrandomvariablesifanyeventAdefinedintermsofXisindependentofanyeventBdefinedintermsofY.(

)第14题TrueorFalse:TherandomvariablesXandYareindependentifandonlyiftheirjointcdfisequaltotheproductofitsmarginalcdf’s.(

)第15题TrueorFalse:IfXandYareindependentdiscreterandomvariables,thenthejointpmfisequaltotheproductofthemarginalpmf’s.()第16题TrueorFalse:IfthejointpmfofdiscreterandomvariablesXandYequalstheproductofthemarginalpmf’s,thenXandYareindependent.(

)第17题TrueorFalse:IfXandYareindependentrandomvariables,thentherandomvariablesdefinedbyanypairoffunctionsg(X)andh(Y)arealsoindependent.(

)第18题TrueorFalse:Forbivariatenormaldistribution,XandYareindependentifandonlyif.(

)

第19题Ifthejointpdfoftwor.v.’sisgivenby,thenrvXandYareindependent.第20题Ifthejointpdfoftwor.v.’sisgivenby,thenthemarginalpdfofXis

f(x)=2e−2xforx>0and0otherwise.Quiz4第1题Theexpectedvalueofarandomvariableisthe()Avaluethathasthehighestprobabilityofoccurring.Bmeanvalueoveraninfinitenumberofobservationsofthevariable.Clargestvaluethatwilleveroccur.Dmostcommonvalueoveraninfinitenumberofobservationsofthevariable.第2题IfXandYareindependentrandomvariables,thenwhichofthefollowingisTRUE?().AE(XY)=E(X)E(Y)

[ErepresentsExpectationvalue]BCov(X,Y)=0

[Covrepresentscovariancebetweenvariables]CVar(X+Y)=Var(X)+Var(Y)

[Varrepresentsvariance]DAlloftheabove第3题Acontractorisconsideringasalethatpromisesaprofitof$38,000

withaprobabilityof0.7oraloss

-duetobadweather,strikes,andsuch-

of$16,000withaprobabilityof0.3.

Whatistheexpectedprofit?

（）A$26,600B$22,000C$37,800D$21,800第4题Abankoffersfreecoffeetoitscustomers.Thecoffeeisbrewedeachmorninginalargecoffeeurn,andtheamountbrewedvariesslightly.Itisindependentfromdaytoday,withmeanof125ouncesandstandarddeviationof3ounces.Theamountcustomersdrinkfromdaytodayisalsorandom,withmeanof100ouncesandstandarddeviationof5ounces,andisindependentoftheamountbrewed.Whatisthemeanandstandarddeviationfortheamountofcoffeeremainingattheendoftheday?()AMean=25ounces,standarddeviation=sqrt(5-3)=1.41ouncesBMean=25ounces,standarddeviation=sqrt(5+3)=2.83ouncesCMean=25ounces,standarddeviation=sqrt(5^2-3^2)=4ouncesDMean=25ounces,standarddeviation=sqrt(5^2+3^2)=5.83ounces第5题Theprobabilityisp=0.80

thatapatientwithacertaindiseasewillbesuccessfullytreatedwithanewmedicaltreatment.Supposethatthetreatmentisusedon40patients.Whatisthe"expectedvalue"ofthenumberofpatientswhoaresuccessfullytreated?()A40B20C8D32第6题Supposethatastudentneedstobuy6booksforhisEnglishcourse.ThenumberofbooksthathewillbeabletofindusedisabinomialrandomvariableXwithn=6andp=0.30.

Inotherwords,theprobabilitythathewillfindanygivenbookusedis0.30,andisindependentfromonebooktothenext.Whatistheexpectednumberofusedbookshewillfind,E(X)?()A1.8B2.0C3.0D6.0第7题Supposethatastudentneedstobuy6booksforhisEnglishcourse.ThenumberofbooksthathewillbeabletofindusedisabinomialrandomvariableXwithn=6andp=0.30.

Inotherwords,theprobabilitythathewillfindanygivenbookusedis0.30,andisindependentfromonebooktothenext.

Whatisthevarianceforthenumberofusedbookshewillfind,Var(X)?()A0.54B1.12C1.26D61.80第8题Acompanymanufacturesbatteriesinbatchesof18andthereisa3%rateofdefects.Findthestandarddeviationforthenumberofdefectsperbatch().A0.721B0.735C0.703D0.724第9题Inordertobeacceptedintoatopuniversity,applicantsmustscorewithinthetop5%ontheentranceexam.Giventhatthetesthasameanof1000andastandarddeviationof200,whatisthelowestpossiblescoreastudentneedstoqualifyforacceptanceintotheUniversity?()A1330B1400C1250D1100第10题LetXandYbenormalrandomvariableswiththeirrespectivemeans3and4andvariances9and16,then2X-Ywillhavenormaldistributionwithparameters().AMean=2andVariance=52BMean=0andVariance=1CMean=2andVariance=1DNoneoftheabove第11题LetXandYbetworandomvariablesandleta,b,c,dberealnumbers,thenwhichoneofthefollowingisFALSE?（）ACov(X+b,Y+d)=Cov(X,Y)BCov(aX,cY)=acCov(X,Y)CCov(aX+b,cY+d)=acCov(X,Y)DCorr(aX+b,cY+d)=acCorr(X,Y)fora,c>0第12题LetXandYbejointly(bivariate)normalwithVar(X)=Var(Y),then().AX+YandX-YarejointlynormalBX+YandX-YareuncorrelatedCX+YandX-YareindependentDAlloftheabove第13题LetXandYbeindependentuniform(0,1)randomvariables.DefineA=X+YandB=X-Y.Then（）.AAandBareindependentrandomvariablesBAandBareuncorrelatedrandomvariablesCAandBarebothuniforms(0,1)randomvariablesDNoneoftheabove第14题TrueorFalse:Theuseoftheterm“expectedvalue”meansthatweexpecttoobserveE[X]whenweperformtheexperimentthatgeneratesX.(

)

第15题TrueorFalse:Regardlessofindependence,theexpectedvalueofasumofnrandomvariablesisequaltothesumoftheexpectedvalues.(

)第16题TrueorFalse:Ingeneral,thevarianceofasumofrandomvariablesisalsoequaltothesumoftheindividualvariances.(

)第17题TrueorFalse:Ingeneral,thevarianceofasumofrandomvariablesisnotequaltothesumoftheindividualvariances.(

)第18题TrueorFalse:LetXhasuniformdistributionU(a,b)suchthatE(X)=2andVar(X)=3/4,thenP(X<1)=1/6.(

)第19题TrueorFalse:Alinearcombinationofnormallydistributedrandomvariablesalsohasanormaldistribution.()第20题TrueorFalse:IfXandYarejointlyGaussianandthecorrelationcoefficientiszero,thenXandYareindependentrandomvariables.(

)第21题TrueorFalse:Thecorrelationassumesvaluesbetween-1and1.(

)第22题TrueorFalse:Acorrelationvaluecloseto1impliesastrongpositiverelationshipbetweentheserv's.(

)第23题TrueorFalse:Acorrelationvaluecloseto-1impliesastrongnegativerelationshipbetweentheserv’s.(

)第24题TrueorFalse:Thecorrelationassumesvalue0meanstherv’sareindependent.()第25题TrueorFalse:ThecorrelationcoefficientbetweenX+YandX-Y,whereXandYareindependentrandomvariableswithvariances36and16respectivelyis6/13.(

)第26题TrueorFalse:IfXandYareuncorrelated,thenXandYareindependentrandomvariables.(

)第27题TrueorFalse:IfXandYareindependent,thenXandYareuncorrelated.(

)第28题TrueorFalse:ItispossibleforXandYtobeuncorrelatedbutnotindependent.(

)第29题TrueorFalse:Thecovarianceandthecorrelationcoefficientoftworandomvariablesaremeasuresofthelineardependencebetweentherandomvariables.(

)第30题TrueorFalse:Themean,variance,andmomentsofarandomvariablesummarizesomeoftheinformationabouttherandomvariableX.(

)下载视频

Quiz5第1题Forthebinomialdistributionwiththegivenvaluesfornandp,statewhetherornotitissuitabletousethenormaldistributionasanapproximation.n=55andp=0.6.

()ANormalapproximationisnotsuitable.BNormalapproximationissuitable.CNotsure.第2题Thenormalapproximationtothebinomialdistributionismostusefulforfindingwhichofthefollowing?()ATheprobabilityP(X=k)whenXisabinomialrandomvariablewithsmalln.BTheprobabilityP(X£k)whenXisabinomialrandomvariablewithlargen.CTheprobabilityP(X=k)whenXisanormalrandomvariablewithsmalln.DTheprobabilityP(X£k)whenXisanormalrandomvariablewithlargen.第3题Thenumberoffirst-yearstudentswhowilldecidetoliveindormitoriesisabinomialrandomvariableXwithn=1000andp=0.50.UsethenormalapproximationwithcontinuitycorrectiontoapproximatetheprobabilitythatXwillbenomorethan490,P(X≤490).

(

)A0.2743B0.2709C0.7291D0.7357第4题Estimatetheindicatedprobabilitybyusingthenormaldistributionasanapproximationtothebinomialdistribution.Aproductismanufacturedinbatchesof120andtheoverallrateofdefectsis5%.Estimatetheprobabilitythatarandomlyselectedbatchcontainsmorethan6defects().A0.4641B0.5871C0.0832D0.4168第5题Supposethataquizconsistsof20True-Falsequestions.Astudenthasn'tstudiedfortheexamandwilljustrandomlyguessatallanswers,i.e.withTrueandFalseequallylikely.Howwouldyoufindtheprobabilitythatthewillstudentget8orfeweranswerscorrect?（）AFindtheprobabilitythatX=8inabinomialdistributionwithn=20andp=0.5.BFindtheareabetween0and8inauniformdistributionthatgoesfrom0to20.CFindtheprobabilitythatX=8foranormaldistributionwithmeanof10andstandarddeviationofsqrt(5).DFindthecumulativeprobabilityfor8inabinomialdistributionwithn=20andp=0.5.第6题Usethenormaldistributiontoapproximatethedesiredprobability.Acoinistossed20times.Aperson,whoclaimstohaveextrasensoryperception,isaskedtopredicttheoutcomeofeachflipinadvance.Shepredictscorrectlyon16tosses.Whatistheprobabilityofbeingcorrect16ormoretimesbyguessing?Doesthisprobabilityseemtoverifyherclaim?（）A0.0069,noB0.0069,yes

C0.4931,noD0.4931,yes第7题TrueorFalse:ThemeanandvarianceofarandomvariableXdoallowustoobtainboundsforprobabilitiesoftheformP(|X|>=t).(

)第8题TrueorFalse:SupposethatarandomvariableXhaszerovariance;thentheChebyshevinequalityimpliesthattherandomvariableisequaltoitsmeanwithprobabilityone.(

)第9题TrueorFalse:WecanusetheChebyshevinequalitytoprovethatthearithmeticaverageofindependentmeasurementsofthesamerandomvariableishighlylikelytobeclosetotheexpectedvalueoftherandomvariablewhenthenumberofmeasurementsislarge.(

)第10题TrueorFalse:Theweaklawoflargenumbersstatesthatforalargeenoughfixedvalueofn,thesamplemeanusingnsampleswillbeclosetothetruemeanwithhighprobability.(

)第11题TrueorFalse:Theweaklawoflargenumbersdoesnotaddressthequestionaboutwhathappenstothesamplemeanasafunctionofnaswemakeadditionalmeasurements.(

)第12题TrueorFalse:Thearithmeticaverageofindependentmeasurementsofthesamerandomvariableishighlylikelytobeclosetotheexpectedvalueoftherandomvariablewhenthenumberofmeasurementsislarge.(

)第13题TrueorFalse:LetX1,X2,…,Xnbeasequenceofiidrandomvariableswithfinitemeanandfinitevariance,thenthecdfofasuitablynormalizedversionofSn=X1+X2+…+XnapproachesthatofaGaussianrandomvariable.(

)第14题TrueorFalse:Thecdfofasumofiidfinite-mean,finitevariancerandomvariablesapproachesthatofaGaussianrandomvariable.(

)Quiz6第1题Somestatisticalproceduresmovefrompopulationtosample;somemovefromsampletopopulation.Statisticalinferencetakesinformationfromthe()tothe().()Asample;populationBpopulation;sampleCneither第2题Somestatisticalproceduresmovefrompopulationtosample;somemovefromsampletopopulation.Samplingdistributionstakeinformationfromthe()tothe().()Asample;populationBpopulation;sampleCneither第3题Whichofthefollowingisnotameasureofcentrallocation?()AmeanBmedianCvarianceDmode第4题Thestandarddeviationof16measurementsofpeople'sweights(inpounds)iscomputedtobe5.4.Thevarianceofthesemeasurementsis()A2.24B29.16C52.34D256第5题Forarandomlyselectedsampleofn=36men’sheights,itisreportedthatthestandarderrorofthemeanis0.5inches.Threeofthefollowingstatementsaretrue,whileoneisfalse.Whichstatementisfalse?（）AThestandarderror(0.5inches)isanestimatedvalueofthestandarddeviationofthesamplemean.BIfanewsampleofn=36men’sheightsiscollected,thestandarderrorofthemeanmightnotequal0.5inches.COvermanydifferentsamplesofn=36men’sheights,theaveragedifferencebetweenthesamplemeanandpopulationmeanwillberoughly0.5inches.DInabout95%ofallsamplesofn=36men’sheights,thesamplemeanwillbewithin0.5inchesofthepopulationmean.第6题WhichofthefollowingdescribestherelationshipbetweentheCentralLimitTheoremandtheRuleforSampleMeans?

()ATheRuleforSampleMeansfollowsfromtheCentralLimitTheorembydividingeachobservationinthesamplebyn.BTheCentralLimitTheoremisaspecialcaseoftheRuleforSampleMeans.CThereisnorelationshipbecausetheCentralLimitTheoremisaboutpopulationmeansandtheRuleforSampleMeansisaboutsamplemeans.DTheCentralLimitTheoremisjustarestatementoftheRuleforSampleMeans.第7题TrueorFalse:LetX1,…,Xnbeasetofindependentobservationsfromanormal

distributionN(m,s2).ThenthemeanofthesamplevarianceS2iss2.

(

)第8题TrueorFalse:Thesamplemeanisitselfarandomvariable,soitwillexhibitrandomvariation.()第9题TrueorFalse:Foranindependentrandomsmaple

fromadistributionwithmeanandvariance,thesamplingdistributionfor

hastheproperty.()第10题TrueorFalse:Foranindependentrandomsample

fromadistributionwithmeanuandvariance,thesamplingdistributionfor

hastheproperty.(

)第11题TrueorFalse:Foranindependentrandom

fromanormaldistributionwithmeanandvariance,thesamplingdistributionfor

hastheproperty

regardlessofthesizeofn()第12题TrueorFalse:If

arei.i.d.as,then

,where.()第13题TrueorFalse:If

arei.i.d.asN[0,1],then

fori=1,2,…,n.

()第14题TrueorFalse:LetXhasanormaldistributionwithparametersμandσ2,

thenX2

followsachi-squaredistributionwithparameter1.(

)第15题TrueorFalse:If

arei.i.d.asN[0,1],then

.(

)第16题TrueorFalse:

If

arei.i.d.N[]where

m

isunknown,then()第17题TrueorFalse:If

then.

()第18题TrueorFalse:Supposethat,

then(

)第19题TrueorFalse:Supposethat.Then(

)第20题TrueorFalse:Thelower100apercentagepointforthe

distributionisthereciprocaloftheupper100apercentagepointofthe

distribution.()Quiz7第1题Asamplestatisticisanunbiasedestimatorofthepopulationparameterif()AtheexpectedvalueofthesamplestatisticisequaltozeroBtheexpectedvalueofthesamplestatisticisequaltooneCtheexpectedvalueofthesamplestatisticisequaltothepopulationparameterDitisequaltozero第2题Apropertyofapointestimatorthatoccurswheneverlargersamplesizestendtoprovidepointestimatesclosertothepopulationparameterisknownas____AefficiencyBunbiasedsamplingCconsistencyDrelativeestimation第3题Usethegivendegreeofconfidenceandsampledatatoconstructaconfidenceintervalforthepopulationmeanμ.Assumethatthepopulationhasanormaldistribution.Asavingsandloanassociationneedsinformationconcerningthecheckingaccountbalancesofitslocalcustomers.Arandomsampleof14accountswascheckedandyieldedameanbalanceof664.14andastandarddeviationof297.29.Finda98%confidenceintervalforthetruemeancheckingaccountbalanceforlocalcustomers（）.Aμ492.52<μ<835.76Bμ493.71<μ<834.57Cμ453.59<μ<874.69D$455.65<<$872.63第4题Arandomlyselectedsampleof400studentsatauniversitywith16-weeksemesterswasaskedwhetherornottheythinkthesemestershouldbeshortenedto14weeks(withlongerclasses).46%ofthe400studentssurveyedansweredyes.Whichoneofthefollowingstatementsaboutthenumber46%iscorrect?()AItisasamplestatistic.BItisapopulationparameter.CItisamarginoferror.DItisastandarderror.第5题Arandomlyselectedsampleof400studentsatauniversitywith16-weeksemesterswasaskedwhetherornottheythinkthesemestershouldbeshortenedto14weeks(withlongerclasses).46%ofthe400studentssurveyedansweredyes.Whichoneofthefollowingdescriptionofthenumber46%isnotcorrect?()ApointestimateBpopulationparameterCsampleestimateDsamplestatistic第6题TrueorFalse:Thesamplemeanisanunbiasedestimatorforthepopulationmean.(

)第7题TrueorFalse:Thesamplevarianceisanunbiasedestimatorforthepopulationvariance.()第8题TrueorFalse:Thesmallerthesamplingvariabilityis,thebetteranunbiasedestimatewillbe.

()第9题TrueorFalse:Aconfidenceintervaliscomputedbasedonasamplestatisticandtheresultisusedtoestimateapopulationparameter.(

)第10题TrueorFalse:Increasingthesamplesizeofasurveydecreasesthemarginoferror.(

)第11题TrueorFalse:Letbearandomsamplefromthepopulationwithpdf.Thenisabiased

estimatorfor.(

)第12题TrueorFalse:Themomentestimatorisuniqueifitexists.(

)第13题TrueorFalse:A

t-intervalisaconfidenceintervalestimateofasamplemean.(

)第14题TrueorFalse:Inintervalestimation,astheconfidencelevelincreasesthemarginoferrordecreases.(

)第15题TrueorFalse:Basedonarandomsampleof101flights,theaverageminutesofairbornetimeforanairlinewas116minutes,withastandarddeviationof6minutes.A95%confidenceintervalfortheaverageairbornetimeforthisairlineiswiderthanthe90%confidenceinterval.(

)第16题TrueorFalse:The95%confidencelevelmeansthat,inthelongrun,theprocedureusedtodeterminetheintervalwillprovideanintervalthatcapturesthepopulationvalueabout95%ofthetime.(

)第17题TrueorFalse:Theconfidencelevelforaconfidenceintervalforameanistheprobabilitytheprocedureprovidesanintervalthatcoversthepopulationmean.(

)Quiz8第1题OnefatherwantedtomotivatehissontogetthehigherscoresintheUniversityEntranceExam.HepromisedtogivehissonanewPCiftheson’save