(a) Suppose there are two people in a room. What is the probability that they have the same birthday? HINT: Find the probability that they have different birthdays and then use the complement.
(b) Suppose that there are three people in a room. What is the probability that two of them share a birthday? HINT: Find the probability that they each have different birthdays and then use the complement.
(c) Suppose that there are yes you guessed it: four people in a room. What is the probability that two of them share a birthday? HINT: Find the probability that they each have different birthdays and then use the complement.
(d) Now for the kicker. What is the minimum number of people that must be in a room together before there is a better-than-not chance of a shared birthday? (By this, I mean a greater than 0.50 probability that two people DO share a birthday)