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Possible Duplicate:
The Monty Hall problem

Three envelopes are presented in front of you by an interviewer. One contains a job offer, the other two contain rejection letters. You pick one of the envelopes. The interviewer then shows you the contents of one of the other envelopes, which is a rejection letter. The interviewer now gives you the opportunity to switch envelope choices. Should you switch?

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marked as duplicate by Marvis, Peter Smith, Henry T. Horton, Alexander Gruber, Micah Jan 14 '13 at 23:21

This question was marked as an exact duplicate of an existing question.

@Marvis Sounds about right. – joejacobz Jan 14 '13 at 22:35
Sorry didn't see that, I will vote to close the question. – fosho Jan 14 '13 at 22:38
up vote 0 down vote accepted

yea u should

P of correct envelope the first time you picked is 1/3

That 1/3 has not changed so by switching you essentially make a switch with a P of 1/2.

Or something along those lines.

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