Curtis Cappell wrote:
>
> Here is just one more way of looking at the 3 doors problem:
>
> Say every contestant chooses not to switch.  Then they will win, on average,
> 1/3 of the time, which is their probability of winning when they first
> picked their door, even if Monty reveals one of the empty doors.
>
> The converse to not switching, provided everything else stays the same
> (Monty always reveals an empty door), is switching.  The converse
> probability to 1/3 (not switching) is 1 - 1/3, or 2/3 (switching).  It is
> better to switch.  Marilyn was correct.
>

Agreed. 1/3 I'm right, 2/3 I'm wrong, take the other door.

The view that the odds are 1/2 would be true *only if* Monty was allowed
to move (if he wished) the prize after the 1st pick and before the 2nd.