Question

What is the probability that at least five persons have the same birthday?

Answer 1

Answer:

Since all probabilities are independent, we can calculate p = (1 - 1/365)*(1 - 2/365) = 132,132/133,225 ~ 0.99159. So, the probability of at least 2 of them having the same birthday (assuming independence) is 1 - p = 1,093/133,225 ~ 0.00820, close to 1 in 122.