设随机变量X的分布律为X为-1,0,1,2时P为1/8,1/2,1/8,1/4 求E(X),E(X^2)
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设随机变量X的分布律为X为-1,0,1,2时P为1/8,1/2,1/8,1/4 求E(X),E(X^2)
设随机变量X的分布律为X为-1,0,1,2时P为1/8,1/2,1/8,1/4 求E(X),E(X^2)
设随机变量X的分布律为X为-1,0,1,2时P为1/8,1/2,1/8,1/4 求E(X),E(X^2)
E(X)=(-1)*(1/8)+0*(1/2)+1*(1/8)+2*(1/4)=1/2 ,
X^2 的分布列为
x^2 0 1 4
P 1/2 1/4 1/4
所以 E(X^2) = 0*(1/2)+1*(1/4)+4*(1/4)=5/4 .
E(2X+3)=2E(X)+3=2*(1/2)+3=4 .