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[主观题]
设随机变量X~P(1);则E(X/(1+X))=()
设随机变量X~P(1);则E(X/(1+X))=()
A.e-1
B.e
C.1
D.1/2
查看答案
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A.e-1
B.e
C.1
D.1/2
A.0
B.1
C.2
D.3
设二维随机变量(X,Y)的概率密度为
求:(I)(X,Y)的边缘概率密度fX(x),fY(y);
(II)Z=2X-Y的概率密度fZ(z);
(III)P{Y≤1/2|X≤1/2}.
设P={x|x2—4x+3<0},Q={x|x(x-1)>2},则P∩Q等于()
A.{x|x>3}
B.{x|-1<x<2}
C.{x|2<x<3}
D.{x|1<x<2}
设二维随机变量的分布函数为F(x,y),则随机变量
的分布函数F1(x,y)=_______