Assume that there are 365 days in a year, the probability that a person is born on any given day is the same for all days, and everyone's birthdays...

 Assume that there are 365 days in a year, the probability that a person is born on any given day is the same for all days, and everyone's birthdays are independent.

(a) If there are n people, what is the probability that no one is born in July?

(b) If there are 15 people who are all born in July or August, what is the probability that at least two of these people share the same birthday?

(c) What is the probability that in a room of n people, at least three of them have the same birthday?