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Topic: say I flip a coin 100 times...
Replies: 46   Last Post: Apr 18, 2005 9:42 PM

 Messages: [ Previous | Next ]
 briggs@encompasserve.org Posts: 404 Registered: 12/6/04
Re: say I flip a coin 100 times...
Posted: Apr 13, 2005 8:39 AM

In article <1113379258.158183.322260@g14g2000cwa.googlegroups.com>, "HERC777" <herc777@hotmail.com> writes:
> On average, not the average.
>
> OKAY WELL DONE EVERYBODY.... (can you tell I taught the remedial
>
> So the expected matching is 20 flips long then?

That's the expected longest initial matching. Approximately.

> you flip a bunch of coins.
> a million peole flip a bunch of coins
>
> whats the expected match length?

If you're asking for the longest match length, irrespective of
starting position and irrespective of which pair of people get the
match, I get 50 coins, give or take.

You have 1,000,001 flippers. Which means that there are
1,000,001 * 1,000,000 / 2 possible pairings of sequences.
And for each pairing of sequences there are 100 * 100 possible
selections of starting position.

That's 20 + 20 - 1 + ~13 = 52 coins.

The true answer is likely a bit lower since a 52 coin match rules
out about half the possible starting positions on each side of each
pairing. So call it 50 coins.

>
> shuddering to think how misinterpreted this will get..

Well, you need to clarify your assumptions up front.

John Briggs

Date Subject Author
4/12/05 HERC777
4/12/05 Jan Burse
4/12/05 HERC777
4/12/05 George Greene
4/13/05 Barb Knox
4/13/05 HERC777
4/13/05 Yajun
4/13/05 HERC777
4/13/05 Jay
4/13/05 HERC777
4/13/05 Jay
4/14/05 Yajun
4/14/05 George Greene
4/14/05 George Greene
4/13/05 Will Twentyman
4/13/05 briggs@encompasserve.org
4/13/05 briggs@encompasserve.org
4/14/05 George Greene
4/14/05 tchow@lsa.umich.edu
4/14/05 briggs@encompasserve.org
4/12/05 Tony
4/13/05 HERC777
4/13/05 ken quirici
4/13/05 Ralph Hartley
4/13/05 Robert Low
4/13/05 Ralph Hartley
4/13/05 Robert Low
4/13/05 tchow@lsa.umich.edu
4/13/05 HERC777
4/13/05 tchow@lsa.umich.edu
4/14/05 HERC777
4/14/05 George Greene
4/14/05 HERC777
4/15/05 tchow@lsa.umich.edu
4/15/05 tchow@lsa.umich.edu
4/16/05 George Greene
4/16/05 HERC777
4/17/05 George Greene
4/17/05 Patricia Shanahan
4/17/05 HERC777
4/18/05 Patricia Shanahan
4/17/05 tchow@lsa.umich.edu
4/18/05 HERC777
4/18/05 George Greene
4/18/05 tchow@lsa.umich.edu
4/18/05 HERC777