【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)]=1
正确
错误
参考答案:
复制
纠错
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)]=0
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
【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
【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)
【简答题】 设随机变量X~U[0,2],则E(X)=[填空1]
【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】 20. Your coat needs to be washed, ______ it?
①  mustn’t
②  needn’t
③  doesn’t
④  can’t
【单选题】 2. I was told yesterday that the company ______ me to Rome next week for a business conference.
①  should have sent
②  was going to send
③  should be sending
④  should send
【单选题】 17.Neither of them ____ the snake.
①  dares catches
②  dare to catch
③  dare catching
④  dare catch
【单选题】 12.You _____ return the book now. You can keep it till next week if you like.
①  cant
②  mustnt
③  neednt
④  may not
【单选题】 6. –Look, someone is coming. Guess who it _____ be?–I think it _____ be Tom.–I don’tthink it _____ be _____.
①  must; can; must; his
②  may; can; must; him
③  must; can; him
④  might; must; can; himself
【单选题】 1. If they ______ to do this work, he might do it some other way.
①  were
②  should
③  will
④  can
【单选题】 8. I______ go to bed until I ______ finished my work last night.
①  Don’t; had
②  didn’t have
③  didn’t; had
④  don’t; have
【单选题】 15.Man _____ die without air or water.
①  will
②  have to
③  must
④  should
【单选题】 16.Let’sclean our classroom, ______?
①  will you
②  dont we
③  shall we
④  do you
【单选题】 7. If it is fine tomorrow, we ______ a football match.
①  have
②  will have
③  has
④  shall has