"How large must a class be to make the probability of finding two people with the same birthday at least 50%?"
I have 360 friends on facebook, and, as expected, the distribution of their birthdays is not uniform at all. I have one day with that has 9 friends with the same birthday. (9 months after big holidays and valentines day seem to be big ones, lol..) So, given that some days are more likely for a birthday, I'm assuming the number of 23 is an upperbound.
Has there been a better estimate to this problem?