Question

A pair of fair dice is rolled and the sum of the numbers is noted. Determine the probability that one die resulted in a 5 given that the sum is 8.

Answer 1

     Pairs whose sum is 8:
     2 + 6,  3 + 5,  4 + 4,  5 + 3,  6 + 2  ( there are 5 pairs )
     Pairs when one die is 5: 3 + 5,  5 + 3 ( 2 pairs )
     P ( A ) = 2 / 5 = 0.4
     Answer: The probability that one die resulted in a 5 given that a sum is 8 is 0.4 .