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Path: utzoo!linus!decvax!harpo!seismo!hao!hplabs!sdcrdcf!darrelj
From: darrelj@sdcrdcf.UUCP (Darrel VanBuer)
Newsgroups: net.math,net.games
Subject: Re: Party game of chance
Message-ID: <838@sdcrdcf.UUCP>
Date: Sun, 12-Feb-84 18:15:40 EST
Article-I.D.: sdcrdcf.838
Posted: Sun Feb 12 18:15:40 1984
Date-Received: Wed, 15-Feb-84 06:14:52 EST
References: <211@heurikon.UUCP>
Reply-To: darrelj@sdcrdcf.UUCP (Darrel VanBuer)
Organization: System Development Corporation, Santa Monica
Lines: 14

The probability of adding the m-th person to a set of people with different
birthday is (roughly) (366-m)/365 [ignores leap year, assumes all dates
equally likely].  So the probabily of a set of m all different is
(364 * 363 * 362 * ... 366-m)/365**(m-1).  This works out to about 50% at 25
people and not quite certain at 50 people.

-- 
Darrel J. Van Buer, PhD
System Development Corp.
2500 Colorado Ave
Santa Monica, CA 90406
(213)820-4111 x5449
...{allegra,burdvax,cbosgd,hplabs,ihnp4,sdccsu3,trw-unix}!sdcrdcf!darrelj
VANBUER@USC-ECL.ARPA