> Only had a quick look at this, but the logic seems flawed to me. 
>    
>   Under Solution, option 1 is in fact two options:
>   1a. Player picks car. Host revealr Goat A. Switching loses.
>   1b. Player picks car. Host reveals Goat B. Switching loses.
>   2. Player picks Goat A. Host must reveal Goat B. Switching wins.
>   3. Player picks Goat B. Host must reveal Goat A. Switching wins.
>    
>   Thus the chances of winning by switching are 50/50. 
>    
>   Anyone agree?

Not me. The total chance in 1a + 1b together is 1/3, 2 is 1/3, and 3 is
the remaining 1/3. So the chance of losing by switching is 1/3, the
chance of winning is 2/3.

Another way to see it (as also explained in the wiki): you pick a door.
now if, after that, you were (always!) offered to pick the other two
doors together, instead of your one door, what would you do? That is the
essentially the same option you get when the host shows one goat and
allows you to pick the other door.

Wouter van Ooijen

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Van Ooijen Technische Informatica: www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: www.voti.nl/hvu
 
 

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