已知随机变量X
1
与X
2
相互独立且有相同的分布：P{X
i
=一1}=P{X
i
=1}=
【正确答案】
A
【答案解析】解析：根据题设知X
1
X
2
可取一1，1，且 P{X
1
X
2
=一1}=P{X
1
=一1，X
2
=1}+P{X
1
=1，X
2
=一1} =P{X
1
=一1}P{X
2
=1}+P{X
1
=1}P{X
2
=一1} =
又 P{X
1
=一1，X
1
X
2
=一1}=P{X
1
=一1，X
2
=1}=
所以X
1
与X
1
X
2
的概率分布为
又 P{X
1
=一1，X
1
X
2
=一1}=P{X
1
=一1，X
2
=1}=
所以X
1
与X
1
X
2
的概率分布为