题目
题型:江西难度:来源:
1 |
2 |
(1)写出ξ的分布列;
(2)求数学期望Eξ.
答案
P(ξ=0)=
1 |
2 |
1 |
2 |
1 |
2 |
1 |
2 |
1 |
2 |
1 |
2 |
1 |
64 |
=C | 13 |
×C | 12 |
1 |
2 |
1 |
2 |
1 |
2 |
1 |
2 |
1 |
2 |
1 |
2 |
3 |
32 |
依此类推P(ξ=10)=
15 |
64 |
5 |
16 |
P(ξ=20)=
15 |
64 |
3 |
32 |
1 |
64 |
所以其分布列为:
1 |
2 |
1 |
2 |
1 |
2 |
1 |
2 |
1 |
2 |
1 |
2 |
1 |
2 |
1 |
64 |
=C | 13 |
×C | 12 |
1 |
2 |
1 |
2 |
1 |
2 |
1 |
2 |
1 |
2 |
1 |
2 |
3 |
32 |
15 |
64 |
5 |
16 |
15 |
64 |
3 |
32 |
1 |
64 |