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There's a famous riddle that involves giving people a choice of 3 envelopes, one of which contains a dollar, and after the person selects an envelope one of the other two is removed and the person is given the option to switch. Is anyone familiar with this and what the math behind it is?


marked as duplicate by whuber Feb 15 '15 at 16:34

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    $\begingroup$ It's the Monty Hall problem: en.wikipedia.org/wiki/Monty_Hall_problem $\endgroup$ – ATJ Feb 15 '15 at 3:41
  • $\begingroup$ It sounds like the Monty Hall problem, but it would only be equivalent if the envelope removed can be assumed to not contain the dollar. $\endgroup$ – Gavin Simpson Feb 15 '15 at 3:57
  • $\begingroup$ @GavinSimpson yes the one removed if I remember correctly is the one that is empty $\endgroup$ – y.lub Feb 15 '15 at 4:00

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