🚀 go-pugleaf

worden@bouncer.nsc.com (Dennis Worden) writes:


>|> The fact that the door which used to be closed is now known to be a loser
>|> is new information.  Specifically, if I guessed a goat (probability 2/3),
>|> then he's now shown me where the winner is.

>The fact that you now have an open door with a goat behind it does not
>change the fact that you have 2 door and 1 prize.  The opening of the
>third door only tells you that the prize is not behind that door, it does
>not add any information as to where the prize really is.

It most certainly does!  If you initially guessed wrong (2/3s chance) which
door Monty opens tells exactly where the prize is, it's the door he didn't
open!  The other 1/3 of the time you initially picked correctly and the prize
is behind your door.  So it boils down to, 2/3 chance the prize is behind
the door no one picked, 1/3 chance the prize is behind the door you initially
picked.

BTW, the game where the contestant does not make an initial pick so
Monty starts things off by revealing a goat is not the same, as which door
the contestant picks *determines* which door Monty picks, unless the
contestant initially picks correctly.

-Mike