Re: I strongly disagree with Lee's answer

From: Adrian Tymes (
Date: Mon May 14 2001 - 10:57:15 MDT

Jeff Davis wrote:
> Good work Adrian, but, I'm scratching my head, because it seems to me that
> you missed the one sequence that represents the original puzzle.
> Contestant chooses door. Host chooses a nonprize door from the unchosen
> two. Contestant switches from his first choice to the other unrevealed
> door.
> Am I missing something?

I was leaving that one out since I thought everyone already knew that
one, but since you asked...

Case E: Host reveals a door other than the one the contestant picked.
If the contestant picked a non-prize, host reveals the other non-prize,
and contestant switches (thus to the prize). If contestant picked the
prize, host reveals a random non-prize, and contestant switches to the
other non-prize.

Trial 1 2 3 4 5 Total WinRatio ExpectedWinRatio
CaseE 646 689 642 671 669 3371 0.6634 0.6666

sub do_strategy_e {
     # host reveals a non-prize door
     my ($picked,$prize) = @_;
     if ($picked != $prize) {
          # host never reveals contestant's door if
          # contestant chose non-prize, so contestant switches
          # to prize
          return $prize;
     } else {
          # host reveals random other door if contestant
          # chose prize, so contestant switches to the
          # other non-prize
          my $new_pick = pick_other_than($picked);
          return $new_pick;

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