The Birthday Problem This classic problem wonders how many people need to be in a group in order to have a greater
than 50% chance that at least two of them share a birthday. Answer each of the following
questions below to explore this problem.
1. To find the probability that “at least two people share a birthday” we will examine its
complement. How would you describe this complement in words?
2. We’ll begin by looking at a group of two people. What is the probability that these two
people do NOT share a birthday?
3. Given your answer to question #2, what is the probability that these two people DO
share a birthday?