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Old 12-17-2004, 12:34 PM  
chodadog
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Join Date: Apr 2002
Posts: 9,736
Quote:
Originally posted by woj
3 boxes (ABC) and 3 different ways to arrange the winning box (xyz)

ABC
x 100
y 010
z 001

You pick A box each time and don't switch:
x: host reveals C is not a winner, you don't switch, you WIN
y: host reveals C is not a winner, you don't switch, you LOSE
z: host reveals B is not a winner, you don't switch, you LOSE

You win 1/3 of the time.


You pick A box each time and you switch:
x: host reveals C is not a winner, you switch, you LOSE
y: host reveals C is not a winner, you switch, you WIN
z: host reveals B is not a winner, you switch, you WIN

You win 2/3 of the time.

Total probability: 1/3+2/3=1


Initially picking B or C doesn't effect this result so by switching
you increase your chances to 2/3.
But from what everyone has been saying, you're supposed to end up with a 50% chance of winning instead of a 33% chance. You've got a 66% chance of winning on the switch.

And what you just wrote up there made no sense to me whatsoever.
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