Quote Originally Posted by jemidiah
I hate to say this, but the leap year gets even more complicated than that

I can never remember it right, but I think it's once every 400 years you skip a leap year. The actual solar year is closer to 365.242 days, not 365.25.

So, in essence, the decimals don't matter. At least to me
Well thats all moot considering that people are more likely to be born on say the spring. So you'd have to do a survey on what days are more likely for people to be born on, which is directly related to the fact that people tend to get married during a certain season.

To get an exact probability, you need to know what day every person that can be in that class is born on, then appropriate the weights accordingly.