2012-2013概率 期中试题答案.doc
上传人:sy****28 上传时间:2024-09-13 格式:DOC 页数:3 大小:102KB 金币:16 举报 版权申诉
预览加载中,请您耐心等待几秒...

2012-2013概率 期中试题答案.doc

2012-2013概率期中试题答案.doc

预览

在线预览结束,喜欢就下载吧,查找使用更方便

16 金币

下载此文档

如果您无法下载资料,请参考说明:

1、部分资料下载需要金币,请确保您的账户上有足够的金币

2、已购买过的文档,再次下载不重复扣费

3、资料包下载后请先用软件解压,在使用对应软件打开

I、Completethefollowingblanks(3pointseachblank,18points)1、Supposethatarethreeevents,thentheeventthatthereareatleastoneeventsamongthemoccurscanbeexpressedas__________.2、Ifaremutuallyexclusiveeventsand,then__0.5___;IfA,Bareindependentevents,_0.44______3、Assumethatthehitrateofsomepersonforshootingis0.6.Ifhehasshot4times,theprobabilitythatheatleasthitthetargetonceis__0.9744_______4、ThenumberofphonecallsarrivingataHYPERLINK"http://en.wikipedia.org/wiki/Call_centre"\o"Callcentre"callcentreperminuteisarandomvariable,definedasX,havingthePoissondistributionwith,itsprobabilitydistributionshouldbe__________________5、Suppose,__0.1915____[]II、Calculates(82points)1、Therearetwoboxes,B1andB2.InB1,thereare3redballsand2blackballs.FourredsandtwoblacksareinB2.Thesetwoboxeslooksthesame,andpickoneballoutofoneboxrandomly,then1)findouttheprobabilitythattheballisred;2)iftheballisblack,howpossibleistheballpickedoutofB1?(10points)P(ballisred)=LetAbeblack,thenisred,2、Thereare10ballswithsixredsandfourgreens.Ifthreeofthese10areselectedrandomlywithoutreplacement,whatistheprobabilitydistributionofthenumbersofgreenballschosen?(10points)X0123p1/61/23/101/303、SupposeXisacontinuousrandomvariablewithprobabilitydensityfunction,then1)findk;2)determinethecumulativedistributionfunctionofX[hint:F(x)];3)calculate.(20points)k=2(归一性)P(0.7<x<1.5)=1-0.49=0.514、AssumeadiscreterandomvariableXhasaprobabilitydistributionX024p0.20.40.4determinetheprobabilitydistributionofY,which(8points)Y04P0.40.65、Thejointprobabilitymassfunctionof(X,Y)isgivenbyXY01211/81/41/831/8αβandsupposeXandYareindependent,1)findαandβ;2)determinetheconditionalprobabilitydistributionofXundertheconditionthatY=1.[hint:](14points)1)2)6、Supposeatwo-dimensionalrandomvariable(X,Y)hasauniformdistributionon,tryto1)calculate,where;2)findoutwhetherXandYareindependent?(20points)1)2)independentExtracredit:(10points)ThelifetimeXofcertainelectronictubescanapproximatedbytheexponentialprobabilitydensityfunction,,pleasefindthepro