Question

投掷两枚匀称骰子，求所掷得的两点数之和为质数的概率。

Answer 1

每粒骰 1 点至 6 点，所以两粒骰共有 36 个排列： (1
1) (1
2) (1
3) (1
4) (1
5) (1
6) (2
1) (2
2) (2
3) (2
4) (2
5) (2
6) (3
1) (3
2) (3
3) (3
4) (3
5) (3
6) (4
1) (4
2) (4
3) (4
4) (4
5) (4
6) (5
1) (5
2) (5
3) (5
4) (5
5) (5
6) (6
1) (6
2) (6
3) (6
4) (6
5) (6
6) 其和为质数，共有 15 个排列： (1
1) → 2 点 (1
2) (2
1) → 3 点 (1
4) (4
1) (2
3) (3
2) → 5 点 (1
6) (6
1) (2
5) (5
2) (3
4) (4
3) → 7 点 (5
6) (6
5) → 11 点 概率 = 15/36 = 5/12 =