Friday, April 24, 2009

Contest 6

The prize for this is the best yet... one FREE night of room AND board in our guest room. Remember that Saturday night stays include your choice of eggs, waffles, french toast or pancakes on Sunday morning.

The rules are a bit different this time:

  • you may not use google, wikiepedia or other online sources

  • you may not look in your old college probability textbook

  • only one entry per person

  • you must answer both parts correctly


Say that a woman and a man (who are unrelated) each has two children. We know that at least one of the woman's children is a boy and that the man's oldest child is a boy. What are the odds that 1) the woman has two boys; and 2) that the man has two boys?

10 comments:

  1. I would love to come to Seattle for a visit and some french toast, but I have absolutely no idea how to figure this one out, which will surprise no one in my family. However, I'll guess each one has a 50/50 chance of having two boys.
    Carol

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  2. Question:
    Is birth order a consideration?

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  3. yes. are you looking for a hint? try writing out all of the possible combinations and probabilities of each.

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  4. I'm sorry, the question is not clear to me. Is question 2 independent of question 1, or does the "and" mean that question 2 is: the woman has 2 boys and the man has 2 boys.

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  5. you got it! good thing too because you're about the only one who can redeem this prize.

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  6. Yay! Just in the nick of time! I'm thinking waffles, unless we have potatoes with the eggs.

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