Quote:
Originally Posted by omk3
Oh great. Three people, three different answers, and that's only for the first two, 'simpler' stages.  |
Actually, I think this moving us on.
The first answer of 1/4, I'm confident of, since that is based on the importance of order (something tells me this is related to the difference between permutations and combinations....)
Anyhow, my first attempt at the second answer ignored order, and I think that was wrong, whereas yours did take it into account. Thus I think that the second answer should be 1/3 as the possibilities are BB BG GB.
If we were to expand the possibilities up each pair would come out to 49 possibilities. B(monday)B(monday), B(monday)B(tuesday), etc. However, we know that at least one boy was born on a tuesday, so the BG can only be expanded up to 7 possibilities each. B(tuesday)G(monday) and so on. By comparison, the BB expands up to 14 possibilities. So we have a total of 28 possibilities.
So the answer to 3 is, I think 1/2. (i.e. 14 out of 28)