Simple Birthday Problem

[skeetshooter]

What is the minimum number of people that you must gather to have a probability that two of them share the same birthday of 1/2? Answer will be posted after a sufficient number of responses, this is pretty easy so sorry if anyone's intelligence is insulted, I'll try to come up with better ones soon.

[AlmightyJay]

To have ANY probability that they share the same birthday? That would be just two people.. I can't imagine this was what you meant, maybe you typoed?

[skeetshooter]

No, the probability must be 1/2 or greater that 2 people share the same birthday(out of all the people in the group). Sorry if that wasn't clear, that was tough to word correctly.

[The Legend]

Take the probability that two people don't have the same birthday, i.e. 364/365. Then given that, prob. that three don't have, i.e. (364/365)*(363/365). continue until it equals less than .5. aka 364!/((364-x)!*365^x))<.5

try 22, and its becomes .49. So the answer is 22 people. Cheers.