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I'm trying to reproduce the 'birthday problem' where you work out the probabilities of n people having the same / different birthday.

Theres a good example here: http://gwydir.demon.co.uk/jo/games/puzzles/birthday.htm

I'm trying to reproduce this in excel and am wondering if anyone knows the various columns and column functions i'd need?

Crizly
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  • Select a random number from 1 to 365(or 366) using the rand function. Do that for ~25 other rows. See if you have a collision(match) – Guy Mar 20 '14 at 15:05

1 Answers1

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You need one column with the values of $n$ and one column with the function that calculates the probabilities. Say, that you have the $n$'s in column A, starting from cell A1. Then write in the cell B1 the following expression

"=(Fact(A1)*Combin(365;A1))/(365^A1)"

which calculates the probability $$p(n)=\frac{n!\dbinom{365}{n}}{365^n}$$ which is the probability that $n$ persons have different birthdays (see Wikipedia for an argumentation of the formula).

Jimmy R.
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