概率问题（混合排列与组合）A和B还有其他8个学生以2人1行,共5行的方式被安排排列在一起照相,求A站在B前面或者背后的概率.A ,B and 8 other students are arranged in 5 rows of 2 in order to take a photography,f

概率问题（混合排列与组合）A和B还有其他8个学生以2人1行,共5行的方式被安排排列在一起照相,求A站在B前面或者背后的概率.A ,B and 8 other students are arranged in 5 rows of 2 in order to take a photography,f
概率问题（混合排列与组合）
A和B还有其他8个学生以2人1行,共5行的方式被安排排列在一起照相,求A站在B前面或者背后的概率.
A ,B and 8 other students are arranged in 5 rows of 2 in order to take a photography,find the probability that A and B are standing in front of or behind each other .
Answer :8/45

概率问题（混合排列与组合）A和B还有其他8个学生以2人1行,共5行的方式被安排排列在一起照相,求A站在B前面或者背后的概率.A ,B and 8 other students are arranged in 5 rows of 2 in order to take a photography,f
C(4,1)*C(2,1)/C(10,2)=4*2/45=8/45