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Topic: Maths question
Replies: 354   Last Post: May 31, 2007 8:04 PM

 Messages: [ Previous | Next ]
 Randy Poe Posts: 5,658 Registered: 12/6/04
Re: Maths question - It's like this
Posted: May 25, 2007 7:46 AM

On May 25, 5:29 am, <BigMama> wrote:
> "none" <""spake\"@(none)"> wrote in messagenews:4656aa25\$0\$30175\$afc38c87@news.optusnet.com.au...
> > Did you read *any* of the previous posts???
>
> Some, but all that talk doesn't change the laws of 2-to-1 probability.
>
> No matter what happens after the first choice, nor how the host acts,
> will change the 2-to-1 odds of the second choice. This is even backed
> up by Occams Razor. Deal with it.

Let's set up a bunch of identical games in identical TV
studios and do the thought experiment. Let's say we have
300 of these games going on.

In all of them, the car is behind door #3.

In 100 studios, the player chooses door #1, in 100 studios
the player chooses door #2, and in 100 studios the
player chooses door #3.

In the first set of studios, the host opens door #2 and
asks the users if they want to change to door #3. 50
say yes, 50 say no.

In the second set of studios, the host opens door #1 and
asks the same question. 50 say yes, 50 say no.

In the third set of studios, the host opens either door
#1 or door #2 and asks the user if they want to change.
50 say yes, 50 say no.

Those who switched: 50 winners in the first set,
50 winners in the second set, 50 losers in the third set.
2/3 of those who switched won.

Those who didn't switch: 50 losers in the first set,
50 losers in the second set, 50 winners in the third
set. 1/3 of those who switched won.

Those are the facts. In a set of random games, those
2/3 of switchers will win, 2/3 of non-switchers will
lose. Deal with it.

Forget trying to reason about probability, just examine
ALL POSSIBLE GAMES (there aren't that many). 2/3
of the switchers will win.

- Randy

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