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| From | Keith Thompson <kst-u@mib.org> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Toughest Probability Question |
| Date | 2011-12-13 10:27 -0800 |
| Organization | None to speak of |
| Message-ID | <ln39co8gyw.fsf@nuthaus.mib.org> (permalink) |
| References | (1 earlier) <4EE69C7E.12EB@mindspring.com> <slrnjedm5u.2as3.usenet-nospam@guild.seebs.net> <h2rde7tob4ibdd18an0opmflg3f4gqf8pk@4ax.com> <slrnjee4qh.2irh.usenet-nospam@guild.seebs.net> <jc7kqo$egv$1@dont-email.me> |
"BartC" <bc@freeuk.com> writes:
> "Seebs" <usenet-nospam@seebs.net> wrote in message
> news:slrnjee4qh.2irh.usenet-nospam@guild.seebs.net...
>> On 2011-12-13, Geoff <geoff@invalid.invalid> wrote:
>
>>> The probability of AT LEAST two of them having the same birthday is
>>> greater than 50% if the number of people is at least 23.
>>
>> Read my post again, please. Not the part where I point out that the
>> problem
>> as stated *does not* specify that the distribution is at all random.
>
> And read the OP's post again:
>
> "before you can be certain that there is a greater than 50/50 chance"
>
> and note the word "chance". With 23 people, the chance IS greater than
> 50%, for certain. What is not for certain is that any two of those
> people WILL have the same birthday.
An annual gathering of the No Two Birthdays Alike club, which has
366 members (and lives up to its name), satisfies the conditions
stated in the problem and results in a 0 probability that at least
two of them have the same birthday.
The probability for 23 people is greater than 50% *if* their
birthdays are random. The author of the problem almost certainly
*intended* to be random, but didn't actually say so.
--
Keith Thompson (The_Other_Keith) kst-u@mib.org <http://www.ghoti.net/~kst>
Will write code for food.
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"
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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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