Quote:
Originally Posted by Rusty
The first person can have any birthday. That gives him 365 possible birthdays out of 365 days, so the probability of the first person having the "right" birthday is 365/365, or 100%.
The chance that the second person has the same birthday is 1/365. So the probability that both people have this birthday, you multiply their separate probabilities. (365/365) * (1/365) = 1/365, or about 0.27%.
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I should have made it the classic birthday problem and given you a group of people and asked the same question. Then you have to handle the different conditional probabilities.
When I was in college, my undergrad prof started out a random processes class with a similar problem trying to prove a point. The funny part is we had a pair of twins in the class. Completely spoiled his thunder
