Expert: Richard J. Raridon - 6/8/2005

Question
What is the probability that at least two people from 24 people have the same birthday?  (Assume 365 days in a year)


P.s. Can you use combination for this problem?

Answer
You have to calculate the probability that none of the people have the same birthday and then subtract that from 1.
The first person can have any day, the next person 364/365, the next 363/365, etc.  
So you multiply together (365/365)(364/365)(363/365)....
for 24 terms and you'll get .4617.  Subtract that from 1 and you'll get .5383 so there's a little better than a
50:50 chance that two people have the same birthday in a group of 24 people.