The correct answer is not 1/2 but 1/3. How can that be? Well there are four possible combinations, BB, GG, BG and GB but but at least one is a boy so you can get rid of GG. So all that's left is BB, BG and GB; and in only one of those three possibilities do I have two boys.
Now I tell you that I have two children and one of them is a boy born on a Tuesday. What is the probability that I have two boys?
