Read the Did You Know? Use this information to calculate the probability that at least two people in your class have the same birthday. Poll your classmates to determine whether two or more of them have the same birthday.

Data from Did You Know:

A mong 24 people chosen at random, what would you guess is the probability that at least 2 of them have the same birthday? It might surprise you to learn that it is greater than 1/2. There are 365 days on which the first person selected can have a birthday. That person has a 365/365 chance of having a birthday on one of those days. The probability that the second person’s birthday is on any other day is 364/365. The probability that the third person’s birthday is on a day different from the first two is 363/365, and so on. The probability that the 24th person has a birthday on any other day than the first 23 people is 342/365. Thus, the probability, P, that of 24 people, no 2 have the same birthday i (365/365)×(364/365)×(363/365)× . . . . . . ×(342/365) = 0.462. Then the probability of at least 2 people of 24 having the same birthday is 1 - P = 1 - 0.462 = 0.538, or slightly larger than 1/2.