Quote:
Originally Posted by SoloAJ
Awesome story. Pretty nice work that you won it every time. How big a favorite is 30?
It's not too hard to work out. The equation for the probability that at least 2 out of N people have the same birthday is just:
1 - (364!/(365^N * (364-N)! ) )
Where the exclamation point denotes a factorial. Essentially, this figures out the probability that no one in a group of N people share the same birthday, and then you subtract it from one. It's only valid for groups smaller than 365 people, but for a group that big, you know the odds that two people share a birthday a priori
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