其中和为6的结果有(1,5),(5,1),(2,4),(4,2),(3,3),共5种,
则所求概率为
5 |
36 |
(Ⅱ)每次从袋中随机抽取2个球,抽到编号为6的球的概率p=
| ||
|
1 |
3 |
所以,3次抽取中,恰有2次抽到6号球的概率为
C | 23 |
1 |
3 |
2 |
3 |
2 |
9 |
(Ⅲ)随机变量X所有可能的取值为3,4,5,6,P(X=3)=
| ||
|
1 |
20 |
| ||
|
3 |
20 |
| ||
|
6 |
20 |
3 |
10 |
| ||
|
10 |
20 |
1 |
2 |
所以,随机变量X的分布列为:
X | 3 | 4 | 5 | 6 | ||||||||
P |
|
|
|
|
5 |
36 |
| ||
|
1 |
3 |
C | 23 |
1 |
3 |
2 |
3 |
2 |
9 |
| ||
|
1 |
20 |
| ||
|
3 |
20 |
| ||
|
6 |
20 |
3 |
10 |
| ||
|
10 |
20 |
1 |
2 |
X | 3 | 4 | 5 | 6 | ||||||||
P |
|
|
|
|