在一个有两个孩子，且至少一个是在星期二出生的男孩的家庭中，另一个也是男孩的概率。

暴力解法

有两个孩子的家庭共有这些情况：

B0B0 B0B1 B0B2 B0B3 B0B4 B0B5 B0B6

B1B0 B1B1 B1B2 B1B3 B1B4 B1B5 B1B6

B2B0 B2B1 B2B2 B2B3 B2B4 B2B5 B2B6

B3B0 B3B1 B3B2 B3B3 B3B4 B3B5 B3B6

B4B0 B4B1 B4B2 B4B3 B4B4 B4B5 B4B6

B5B0 B5B1 B5B2 B5B3 B5B4 B5B5 B5B6

B6B0 B6B1 B6B2 B6B3 B6B4 B6B5 B6B6

;

B0G0 B0G1 B0G2 B0G3 B0G4 B0G5 B0G6

B1G0 B1G1 B1G2 B1G3 B1G4 B1G5 B1G6

B2G0 B2G1 B2G2 B2G3 B2G4 B2G5 B2G6

B3G0 B3G1 B3G2 B3G3 B3G4 B3G5 B3G6

B4G0 B4G1 B4G2 B4G3 B4G4 B4G5 B4G6

B5G0 B5G1 B5G2 B5G3 B5G4 B5G5 B5G6

B6G0 B6G1 B6G2 B6G3 B6G4 B6G5 B6G6

;

G0B0 G0B1 G0B2 G0B3 G0B4 G0B5 G0B6

G1B0 G1B1 G1B2 G1B3 G1B4 G1B5 G1B6

G2B0 G2B1 G2B2 G2B3 G2B4 G2B5 G2B6

G3B0 G3B1 G3B2 G3B3 G3B4 G3B5 G3B6

G4B0 G4B1 G4B2 G4B3 G4B4 G4B5 G4B6

G5B0 G5B1 G5B2 G5B3 G5B4 G5B5 G5B6

G6B0 G6B1 G6B2 G6B3 G6B4 G6B5 G6B6

;

G0G0 G0G1 G0G2 G0G3 G0G4 G0G5 G0G6

G1G0 G1G1 G1G2 G1G3 G1G4 G1G5 G1G6

G2G0 G2G1 G2G2 G2G3 G2G4 G2G5 G2G6

G3G0 G3G1 G3G2 G3G3 G3G4 G3G5 G3G6

G4G0 G4G1 G4G2 G4G3 G4G4 G4G5 G4G6

G5G0 G5G1 G5G2 G5G3 G5G4 G5G5 G5G6

G6G0 G6G1 G6G2 G6G3 G6G4 G6G5 G6G6

其中，至少有一个在星期二出生的男孩的情况有：

B0B2 B1B2 B2B0 B2B1 B2B2 B2B3 B2B4 B2B5 B2B6 B3B2 B4B2 B5B2 B6B2

B2G0 B2G1 B2G2 B2G3 B2G4 B2G5 B2G6 G0B2 G1B2 G2B2 G3B2 G4B2 G5B2 G6B2

最后答案为 13/27

WTF?