For number 18, did you just assume that the probability for each day during the week is 1/7? Because when I was looking at it, I noticed that 366 doesn't divide evenly leaving two days with 53 occurrences and 5 days with 52 occurrences making the probability different. --Podarcze 14:55, 8 October 2008 (UTC)
I just assumed each of the 366 days was equally likely. I calculated the probability none of them had the same birthday and then subtracted that from 1. --Norlow 15:08, 8 October 2008 (UTC)
