#55, RE: Monty Hall Problem
Posted by Seesall on Oct-31-04 at 03:46 PM
In response to message #54
>>>Once again you are not using the lettering system used by >>>Devlin where the letters are not applied until after the >>>choices are made. >> >>That is not true here is what Delvin said: >> >>"Suppose the doors are labeled A, B, and C. Let's assume the >>contestant initially picks door A. The probability that the >>prize is behind door A is 1/3. That means that the >>probability it is behind one of the other two doors (B or C) >>is 2/3. Monty now opens one of the doors B and C to reveal >>that there is no prize there. Let's suppose he opens door >>C." >> >>Delvin did not say that Monty picks one of the two remaining >>doors >>and then labels that door C. >> >> >>>Monty does indeed have a choice between >>>two doors but the labels "B" and "C" are not applied until >>>after the contestant choses door "A" and Monty next opens a >>>door. Regardless of which door Monty opens that door is >>>labeled "C" and the remaining door is labeled "B". >> >>I agree that such a labeling system changes the problem >>but that is not the spirit of the orginial question in which >>three doors each have distinct identities given by A B and C >>or if you prefer 1,2,3. People can judge for themselves what >>they think Delvin really meant. >> >> >The paradox is that with either labeling system the same >fact situation arises and the problem is the same, what is >the probability of "B" at that instant. Using "my" labeling >system one can easily see that by switching, contestants >double their chances of winning. The two labeling systems are completely different. Your system corresponnds to always switch for both doors which averages out to 2/3. You can't relabel door C door B and say its the same! Suppose the contestant chooses A and Monty never chooses C with a car behind A under "my" system. What are the odds on B and C? Door C can never lose....think about it...
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