Re: [積統] 古典機率
※ 引述《KAINTS (RUKAWA)》之銘言：
: ※ [本文轉錄自 Grad-ProbAsk 看板 #1GTDGnD- ]
: 作者: KAINTS (RUKAWA) 看板: Grad-ProbAsk
: 標題: [理工] 機率
: 時間: Wed Oct 10 09:49:35 2012
: Suppose that 20 sticks are broken,each into one long and one short part.
: By pairing them randomly, the 40 parts are then used to make 20 new
: sticks.
: (a) What is the porb. that long parts are all paired with short ones?
: (b) What ia the prob. that the new sticks are exactly the same as the old
: ones?
: 要怎麼解??
(a)40根棍子排成一列的組合: 40!
20組皆為一長一短的組合: 2^20*20!20!
Ans : 2^20*20!20!/40!
(b)原本拆開的全部棍子再組回原本的
40根棍子排成一列的組合: 40!
20組皆為原本長度的棍子: 2^20*20!
Ans : 2^20*20!/40!
有錯請指正
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