[機統] 一個環狀排列的小問題
A total of 2n people, consisting of n married couples, are randomly seated
at a round table but subject to the man and women alternate. Let Ci denote
the event that the ith couple are seated next to each other
(a). P(Ci)=?
(b). P(Ci|Cj)=? (where i≠j)
2
(a) 答案是 ----- 嗎?
n
不曉得是不是我會錯意,有人說可以這樣看P(Ci)
the ith husband
↓
o o
○ o
先擺好n個男的,共有n個空隙,再將女的排入
因為the ith husband旁邊 有兩個空位 所以老婆坐在他旁邊的機率是 2/n
我一直搞不懂為什麼是這樣=.=
(b)我做不出來.. 還請大家幫忙
謝謝
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