Thread: Probability Fun
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Old 06-10-2010, 03:31 PM   #44
LazyScot
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Quote:
Originally Posted by omk3 View Post
Well, I may have found the answer but probabilities still confuse me. 1/2 seems to me as valid as 1/3, and alternative solutions proposed for the third stage sounded equally valid from a specific viewpoint.


I don't really see why the exact same information would produce different probability results depending on how you got the information. The hard facts we get from the Scientific American puzzle and pdurrant's puzzle are exactly the same. Does it really matter how they are presented?
One way of looking at it is that by knowing at least one child is a boy, the probabilities of having a girl child *for that specific person* are no longer 1/2. If they were, they would still have a chance of having 2 girls. What has happened is that we have information that places the person in a subset of the overall population, so the probabilities change.

I think!
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