If a coin is tossed 2,000,000 times, what is the probability that it will come up exactly 1,000,000 times each heads and tails?

From a simple binomial theorem, this answer is


2M * (2M-1) * (2M-2) * ... * (1M+1)


divided by


1 * 2 * 3 * ... * 1M


divided by 2^2M.

This evaluates to about 0.000564.

Posted by Jim Lyon on 2003-03-03 07:58:47