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Re: Toughest Probability Question

From Thad Smith <ThadSmith@acm.org>
Newsgroups comp.lang.c
Subject Re: Toughest Probability Question
Date 2011-12-18 23:34 -0700
Organization Aioe.org NNTP Server
Message-ID <jcmlta$5v2$1@speranza.aioe.org> (permalink)
References (7 earlier) <jc8oom$ku5$2@dont-email.me> <lnaa6w6kyu.fsf@nuthaus.mib.org> <slrnjefueb.ach.usenet-nospam@guild.seebs.net> <784b5cd3-7f5d-499a-9950-1e444abffca4@18g2000prn.googlegroups.com> <af51265f-1b6b-48d0-a132-38f66883de0a@y12g2000vba.googlegroups.com>

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On 12/15/2011 6:38 AM, gwowen wrote:
> On Dec 15, 10:33 am, James Dow Allen<jdallen2...@yahoo.com>  wrote:
>> It's often overlooked that probability fundamentally
>> involves *ignorance*
...
> The probability of a given event is fundamentally the same for
> everyone, but one's estimate of that probability is based on one's own
> information.

Then the probability of having matching birthdays _in a given group_ is either 1 
or 0, depending on the actual birthdays.  To be certain it is greater than 50%, 
one must know the birthdays or know that there are enough people to guarantee it.

I agree with James that the question is poorly worded.  If the question were 
instead "How many randomly selected people must be gathered together in a room 
before there is a greater than 50/50 chance that at least two of
them have the same birthday?", the answer would be different.

Thad

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Thread

Re: Toughest Probability Question pete <pfiland@mindspring.com> - 2011-12-12 19:29 -0500
  Re: Toughest Probability Question Seebs <usenet-nospam@seebs.net> - 2011-12-13 04:46 +0000
    Re: Toughest Probability Question Geoff <geoff@invalid.invalid> - 2011-12-12 22:19 -0800
      Re: Toughest Probability Question Seebs <usenet-nospam@seebs.net> - 2011-12-13 09:19 +0000
        Re: Toughest Probability Question "BartC" <bc@freeuk.com> - 2011-12-13 13:43 +0000
          Re: Toughest Probability Question Keith Thompson <kst-u@mib.org> - 2011-12-13 10:27 -0800
            Re: Toughest Probability Question "BartC" <bc@freeuk.com> - 2011-12-13 19:52 +0000
              Re: Toughest Probability Question Seebs <usenet-nospam@seebs.net> - 2011-12-13 20:06 +0000
              Re: Toughest Probability Question Keith Thompson <kst-u@mib.org> - 2011-12-13 12:14 -0800
                Re: Toughest Probability Question "BartC" <bc@freeuk.com> - 2011-12-13 23:34 +0000
                Re: Toughest Probability Question Seebs <usenet-nospam@seebs.net> - 2011-12-14 00:24 +0000
          Re: Toughest Probability Question Seebs <usenet-nospam@seebs.net> - 2011-12-13 19:27 +0000
            Re: Toughest Probability Question "BartC" <bc@freeuk.com> - 2011-12-13 23:56 +0000
              Re: Toughest Probability Question Seebs <usenet-nospam@seebs.net> - 2011-12-14 00:24 +0000
                Re: Toughest Probability Question "BartC" <bc@freeuk.com> - 2011-12-14 12:12 +0000
                Re: Toughest Probability Question Seebs <usenet-nospam@seebs.net> - 2011-12-14 17:47 +0000
                Re: Toughest Probability Question gordonb.qunma@burditt.org (Gordon Burditt) - 2011-12-15 08:22 -0600
                Re: Toughest Probability Question Robert Wessel <robertwessel2@yahoo.com> - 2011-12-15 14:41 -0600
                Re: Toughest Probability Question superpollo <superpollo@tznvy.pbz> - 2011-12-15 19:14 +0100
                Re: Toughest Probability Question Keith Thompson <kst-u@mib.org> - 2011-12-14 13:12 -0800
                Re: Toughest Probability Question Willem <willem@toad.stack.nl> - 2011-12-14 21:53 +0000
                Re: Toughest Probability Question "BartC" <bc@freeuk.com> - 2011-12-14 22:35 +0000
                Re: Toughest Probability Question Willem <willem@toad.stack.nl> - 2011-12-15 09:07 +0000
                Re: Toughest Probability Question Geoff <geoff@invalid.invalid> - 2011-12-15 02:07 -0800
                Re: Toughest Probability Question Keith Thompson <kst-u@mib.org> - 2011-12-15 12:13 -0800
                Re: Toughest Probability Question Geoff <geoff@invalid.invalid> - 2011-12-15 13:03 -0800
                Re: Toughest Probability Question Seebs <usenet-nospam@seebs.net> - 2011-12-15 21:36 +0000
              Re: Toughest Probability Question Geoff <geoff@invalid.invalid> - 2011-12-13 16:35 -0800
                Re: Toughest Probability Question Seebs <usenet-nospam@seebs.net> - 2011-12-14 01:20 +0000
              Re: Toughest Probability Question Keith Thompson <kst-u@mib.org> - 2011-12-13 16:44 -0800
                Re: Toughest Probability Question Seebs <usenet-nospam@seebs.net> - 2011-12-14 01:20 +0000
                Re: Toughest Probability Question James Dow Allen <jdallen2000@yahoo.com> - 2011-12-15 02:33 -0800
                Re: Toughest Probability Question gwowen <gwowen@gmail.com> - 2011-12-15 05:38 -0800
                Re: Toughest Probability Question Thad Smith <ThadSmith@acm.org> - 2011-12-18 23:34 -0700
                Re: Toughest Probability Question Bill Reid <hormelfree@gmail.com> - 2011-12-14 07:07 -0800
    Re: Toughest Probability Question Kaz Kylheku <kaz@kylheku.com> - 2011-12-13 06:55 +0000
      Re: Toughest Probability Question Seebs <usenet-nospam@seebs.net> - 2011-12-13 09:19 +0000
    Re: Toughest Probability Question pete <pfiland@mindspring.com> - 2011-12-13 12:15 -0500
      Re: Toughest Probability Question pete <pfiland@mindspring.com> - 2011-12-13 13:20 -0500
        Re: Toughest Probability Question Peter Nilsson <airia@acay.com.au> - 2011-12-13 18:15 -0800
          Re: Toughest Probability Question pete <pfiland@mindspring.com> - 2011-12-13 21:52 -0500

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