>Walter,
>
>Al (and others) are right, it makes no difference if you change your guess. Deciding NOT to change doors is also a choice, therefore your chance is always 1/x where x is the number of remaining doors. When Monty Hall opens one of the wrong doors, 'x' is reduced by one. When he gives you a chance to choose again, your chances are 1/x whether you change your guess or not. Changing does not improve your chances.
>
>Note to Dan Cummings: the name of the show was Let's Make a Deal.
>

The trick is: that the host has to show all but one goat-door. In the 3 door case, there is a chance of 2/3 that the host has NO choice, but to show the only remaining goat-door (as in 2/3 of the cases you choose the other goat-door) so:

- in 2/3 of the cases you initially choose a goat-door.

- Given this fact. The host HAS to point out the (only remaining) OTHER goat door. Note that the host doesn't have a choice of wich door to open in 2/3 of the cases. That's the trick !!!

- Resulting in the fact that the other remaining door holds the boat (2/3 chance).


Just write a little VFP program to test this and you'll come to this conclusion.

Walter,