N(-1,2)-|||-D N(0,1)

设X与Y相互独立,且approx N(1,2), _(Delta )N(0,1),令approx N(1,2), _(Delta )N(0,1),则D(Z) =

若_(i)sim N(0,1), =1,2,(X)_(1),(X)_(2)独立，则_(i)sim N(0,1), =1,2,(X)_(1),(X)_(2)()A

A.approx N(0,1)B.approx N(0,1)C.approx N(0,1)D.approx N(0,1)设连续性随机变量X和Y相互独立，且，Y的

设两个相互独立的随机变量X和Y分别服从正态分布N(0,1)和N(0,1)，则（ ）(A)N(0,1)(B)N(0,1)(C)N(0,1)(D)N(0,1)

设随机变量sim N(0,1)，sim N(0,1)，则sim N(0,1).A.1B.-1C.sim N(0,1)D.0设随机变量，，则.A.1B.-1C.D

设随机变量sim N(0,1)，sim N(0,1)，且X与Y相互独立，则sim N(0,1).A.sim N(0,1)B.sim N(0,1)C.sim N(

(mu ,dfrac ({sigma )^2}(n))-|||-C.N(0,1)-|||-D.N(0,σ^2)

xi sim N(0,1) , =2s-1,则xi sim N(0,1) , =2s-1,( )。A.xi sim N(0,1) , =2s-1,B.xi

设随机变量sim N(0,1)，sim N(0,1)为其分布函数，则sim N(0,1).A.1B.0.25C.0.5D.2设随机变量，为其分布函数，则.A.1

随机变量X,Y相互独立且sim N(0,1),sim N(0,1),则下列各式成立的是( )A.sim N(0,1)B.sim N(0,1)C.sim N