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标题: Probability problem [打印本页]

作者: ob 时间: 2004-11-4 22:59
标题: Probability problem

What are the chances that at least two out of a group of fifty people share the same birthday?

作者: ac_x 时间: 2004-11-5 08:27
标题: 回复：Probability problem

P = 1 - P(365,50)/365^50 = 1 - 365!/315!/365^50 = 1 - 0.029626 = 0.970374

P(365,50) is the permutation of all possible ways to distribute 50 b-days. (no repeat)

365^50 represent all possible ways of arranging 50 bdays.

and you will get the probability of more than 1 ppl has the same bday. then subtracted by 1, u will get the answer :D

作者: sean9991 时间: 2004-11-5 18:15
标题: 回复：回复：Probability problem

you forgot if somebody was born in leap year, then his birthday is Feb 29. And the probability of a random people has this birthday is approximately 97/400 of other days.

作者: ac_x 时间: 2004-11-8 02:29
标题: answer is above

answer is above

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