Path: csiph.com!x330-a1.tempe.blueboxinc.net!newsfeed.hal-mli.net!feeder3.hal-mli.net!newsfeed.hal-mli.net!feeder1.hal-mli.net!border3.nntp.dca.giganews.com!Xl.tags.giganews.com!border1.nntp.dca.giganews.com!nntp.giganews.com!local2.nntp.dca.giganews.com!nntp.earthlink.com!news.earthlink.com.POSTED!not-for-mail
NNTP-Posting-Date: Mon, 12 Dec 2011 18:29:59 -0600
Message-ID: <4EE69C7E.12EB@mindspring.com>
Date: Mon, 12 Dec 2011 19:29:50 -0500
From: pete <pfiland@mindspring.com>
Reply-To: pfiland@mindspring.com
Organization: PF
X-Mailer: Mozilla 3.04Gold (WinNT; I)
MIME-Version: 1.0
Newsgroups: comp.lang.c
Subject: Re: Toughest Probability Question
References: <9cb0f967-18d1-410c-9074-f4d84858d9af@u10g2000prl.googlegroups.com>
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Lines: 51
X-Usenet-Provider: http://www.giganews.com
NNTP-Posting-Host: 4.154.220.183
X-Trace: sv3-qrbCO7ijQOWnBb3edFeQrhr+WBMy9DP87/zGKY5T4oz6QOYoGTl+q+NrEf20VBL+UNsMdq6hVkC/25i!PxHovFONgHKKXVAoUaJL0O32HP2kV9D1uqWkioytA/lrFDeJjVj65tB40xKVPz4GMOUNZNBal7na!hw67Iignk1M=
X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers
X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly
X-Postfilter: 1.3.40
X-Original-Bytes: 2136
Xref: x330-a1.tempe.blueboxinc.net comp.lang.c:14536

divya bisht wrote:
> 
> Toughest Probability Question
> (Source : http://hardest-puzzle.blogspot.com/2011/12/toughest-probability-question.html
> )
> 
> How many people must be gathered together in a room, before you can be
> certain that there is a greater than 50/50 chance that at least two of
> them have the same birthday?
> 
> Discuss Solution in link below

/* BEGIN output from new.c */

The probability that 23 random birthdays are all different is 0.492703

/* END output from new.c */



/* BEGIN new.c */

#include <stdio.h>

#define YEAR 365 /* 366 */

int 
main(void)
{
    int days = YEAR;
    double probability = 1;
    int people = 1;
    puts("\n/* BEGIN output from new.c */\n");
    do {
        ++people;
        --days;
        probability *= 1.0 * days / YEAR;
    } while(probability > 0.5);
    printf("The probability that %d "
        "random birthdays are all different is %f\n", 
        people, probability);
    puts("\n/* END output from new.c */");
    return 0;
}

/* END new.c */



-- 
pete