What are the odds? Our small group has two with the same birthday!
This is actually a great mathematical question, Geoff, and one you could easily use in your class sometime.
Imagine a room with one person in it and a line out the door of people who will enter one by one. Obviously the odds of a birthday match increase each time someone enters, but at what point do the odds become better than 50-50? The answer is very counter-intuitive, but easy to prove.
I'll answer you first question specifically about me & Tinka later.