【简答题】【消耗次数:1】
设随机变量X~U[0,2],则E(X)=[填空1]
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相关题目
【简答题】 设随机变量X~U[0,2],则E(X)=[填空]
【简答题】 设随机变量X~U[0,2],则E(X)=[填空]
【单选题】 设随机变量X在区间[0,1]服从均匀分布,则E(2X)= ( )
①  0
②  1/2
③  1
④  2
【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
【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】 设随机变量X和Y独立同分布,记U=X-Y,V=X +Y ,则随机变量U与V也
①  不独立
②  独立
③  相关系数不为零
④  相关系数为零
【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
【单选题】 设随机变量X服从指数分布,则随机变量Y=min(X,2)的分布函数
①  是连续函数
②  至少有两个间断点
③  是阶梯函数
④  恰好有一个间断点
【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
【单选题】 设随机变量X的方差,则X的数学期望()
①  16
②  20
③  4
随机题目
【判断题】 Before he began to study in the university, he had worked in a company for three years.
①  正确
②  错误
【判断题】 My family has lived in Lndon in 1995.
①  正确
②  错误
【判断题】 All of people, includes a child, failed in the computer game.
①  正确
②  错误
【单选题】 _______these people know how to solve this problem.
①  Most of
②  Some
③  Most
【单选题】 It’s very safe_______here.
①  living
②  live
③  lived
【单选题】 The diningroom needs_______.
①  decorating
②  to decorate
③  decorate
【单选题】 I’m ill. I_______working very hard.
①  have
②  have been
③  had
【单选题】 Hetriedhisbesttofinish the work,_______difficultitwas.
①  however
②  nomatter
③  whatever
【单选题】 Lily forgot_______a letter to her sister, so she wrote to her just now.
①  to have written
②  to write
③  having wrote
【单选题】 The museum_______built two years ago.
①  has been
②  was
③  is being