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 Happy Birthday (3) (Posted on 2006-06-09)
In Happy Birthday, the question was if there are N people in a room, what is the probability that there are at least two people in the room who share a birthday?

What if instead exactly two was required? If there are N people in a room, what is the probability that there are exactly two people in the room who share a birthday?

(Note: Assume leap year doesn't exist, and the birthdays are randomly distributed throughout the year.)

 No Solution Yet Submitted by Sir Percivale Rating: 4.0000 (3 votes)

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 re: thoughts | Comment 2 of 12 |
(In reply to thoughts by Bob Smith)

Bob, I disagree. You have to take into account that also the first two people can heva the same birtday. Just multiplying your solution by n/2 (n position to insert the person sharing a birthday with another, divided by two because the two can be interchanged).
 Posted by Robby Goetschalckx on 2006-06-09 08:02:39

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