【判断题】【消耗次数:1】
设随机变量X,Y相互独立,EX=0,EY=1,DX=1,则E[X(X+Y-2)]=0
正确
错误
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相关题目
【判断题】 设随机变量X,Y相互独立,EX=0,EY=1,DX=1,则E[X(X+Y-2)]=1
①  正确
②  错误
【单选题】 若随机变量X,Y相互独立,EX=EY=0,DX=DY=1,则E(X+Y+1)2=
①  2
②  3
③  1/3
④  1
【判断题】 设X、Y是随机变量,若X与Y相互独立,则E(XY)=EX?EY
①  正确
②  错误
【判断题】 设X、Y是随机变量,若E(XY)=EX?EY,则X与Y相互独立.
①  正确
②  错误
【单选题】 X,Y为两个随机变量,且E((X-EX)(Y-EY))=0则X,Y( ).
①  独立
②  不独立
③  相关
④  不相关
【判断题】 随机变量X、Y相互独立,则D(X+Y)=DX+DY.
①  正确
②  错误
【单选题】 设二维随机变量(X,Y)~N(μ1,μ2,σ21,σ21,ρ),且X与Y相互独立,则ρ=( )
①  1
②  0.5
③  0
④  2
【简答题】 设随机变量X~U[0,2],则E(X)=[填空1]
【单选题】 设相互独立的随机变量X,Y均服从(o,1)上的均匀分布,令Z=X+Y则( ).
①  Z也服从(0,1)上的均匀分布
②  P(X=Y)=0
③  Z服从(0,2)上的均匀分布
④  Z~N(1,0)
【判断题】 设X、Y是随机变量,若X与Y相互独立,则E(aX+bY)=aEX+bEY
①  正确
②  错误
随机题目
【单选题】 He was prepared to make the ultimate sacrifice, displaying ?bravery that was second to _________.
①  none
②  neither
③  anything
④  nothing
【单选题】 Did you get a dictionary?No. I________,but there were not any________.
①  tried;to be left;
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③  tried to;left
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【单选题】 Mymotherisno_______ young.
①  shorter
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③  little
④  few
【单选题】 Look,someone is coming. Guess who it_________be?I think it______be Tom.I dont think it______be_______.
①  must;can;must;his
②  may;can;must;him
③  can;must;can;him
④  might;must;can;himself
【单选题】 I will take my daughter with me when I_______ Shanghai.
①  go to
②  will go to
③  have been to
④  have gone to
【单选题】 It was getting dark. I found a car________in a pool by the side of the road.
①  to be stuck
②  stuck
③  sticking
④  stick
【单选题】 This bright girl______ the truth in front of the enemy.
①  didn’t say
②  couldn’t speak to
③  said
④  didn’t tell
【单选题】 ________the front door________,he had to enter the room through the back door.
①  Seen;painted
②  Seeing;painted
③  Being seen;being painted
④  Seeing;being painted
【单选题】 This book is_____that one. But______than that one.
①  as difficult as ;expensive
②  as more difficult as ; more expensive
③  as difficult as ; more expensive
④  more difficult as ; as expensive
【单选题】 It was his fault,but he put the blame on others—thats _______ we cant agree.
①  where
②  what
③  how
④  which