If three standard six-sided dice are rolled, what is the probability that the sum of the numbers on the top faces is 17 or 18?
The probability that this will happen is 1/54. If you count the numer of ways you can get 18 and 17, (6,6,6),(6,6,5),(6,5,6),(5,6,6) that is 4 ways. There are 6^3 = 216 total possibilities 4/216 = 2/108 = 1/54
