Question

若随机变量X服从成功概率为p的两点分布，则下列正确的是(    )

A.EX=p,DX=1-p                             B.EX=1-p,DX=p

C.EX=p,DX=p-p²                            D.EX=1-p,DX=p-p²

Answer 1

思路解析：因为随机变量X服从分布列

X	0	1
P	1-p	p

,所以EX=p,DX=p²(1-p)+(1-p)²p=p(1-p).

答案：C