1−∑[m!n! / {i! (n−2i)! (m−n +i )! 2^i m^n}, m=365, n=30, i=0 to n/2.
This summation formula gives the probability that 3 people out of 30 share the same birthday. Can anyone come with the actual probability in this particular example? My calculators simply can't do 365!. Any help would be appreciated. Thanks a lot.
Wow! That is quite a whopper! I have modified the braces and the brackets slightly to balance them.
I summed it up on Wolfram/Alpha and got this result = 0.0285305 x 100 =2.85305%. You can see it all here:http://www.wolframalpha.com/input/?i=1+-+%E2%88%91365!30!+%2F+%7Bi!+(30-2i)!+(365-30+%2Bi+)!+2%5Ei+365%5E30%7D,+i%3D0+to+15
