Expectation · Birthdays · difficulty 3 of 5
How many different birthdays
There are 30 people in a room. Each person's birthday is equally likely to be any of 365 days (ignore February 29), independently of everyone else. What is the expected number of different birthdays among them?
Answer with an expected value. First lock in a gut guess with an 80% range, then solve it properly, then watch a simulation settle on the truth.
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