If there is a group of n people in a room, what is the probability that two or more of them have the same birthday?

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If there is a group of n people in a room, what is the probability that two or more of them have the same birthday? It is possible to determine this question by simulation. Write a function that calculates the probability that two or more of n people will have the same birthday, when n is a calling argument.
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Answers (2)

Image Analyst
Image Analyst on 31 Aug 2014
As this is most likely a homework problem (and I've tagged it as such), I'll just give you some hints.
n = 30;
birthdays = randi(365, n, 1) % Get list of birthdays out of possible 365 days per year.
counts = histc(birthdays, 1:365) % Count how many people have each birthday.
Put the above in a loop and do it, say, a million times to find the probability that max(counts) >= 2. Try different n also.

Roger Stafford
Roger Stafford on 31 Aug 2014
The probability, P, (in a non-leap year) is:
P = 1 - prod((365:-1:365-n+1)./repmat(365,1,n));

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