数学问题(关于概率与期望值)

1(a) 可能结果(1
5)
(2
4)
(3
3)
(4
2)
(5
1) P(总和为) = 5/36 (b) P(总和小于5) = 1/36 + 2/36 + 3/36 = 1/6 (c) P(总和大于或等于4) = 1 - P(总和小于4) = 1 - 3/36 = 33/36 2(a) 1/36
2/36
3/36
4/36
5/36
6/36
5/36
4/36
3/36
2/36
1/36 (b) 结果的期望值 = (2 * 1 + 3 * 2 + 4 * 3 + ... + 1*12)/36 = 7 3(a) P(三颗骰的结果均相同) = 6/216 = 1/36 (b) P(三颗骰的总和为16) = (3 + 3)/216 = 1/36 4(a) C(13
1)C(4
3)C(48
2)/C(52
5) = 0.02247 (b) C(13
1)C(4
2)C(48
3)/C(52
5) = 0.519 5 出现红色和黑色的机会一样大 6 0.1 * 500 + 0.3 * 700 + 0.2 * 1000 = 50 + 210 + 200 = 460