What is the probability that the sum of outcomes of three dice thrown together is 9?
I happen to know the probability distribution for two dice because I derive it with my students every year.
To add a 3rd die and have the sum be 9, the first two must sum to 3,4,5,6,7or8
(2+3+4+5+6+5)/36 = 25/36
and then for each you have a 1/6 chance of getting the correct sum
25/26*1/6 = 25/216

Posted by Jer
on 20091120 15:14:22 