Question

Two number cubes are rolled. What is the probability that the sum of the numbers rolled is either 4 or 8? A.1/9. B.2/9. C.5/18. D.5/432

Answer 1

There are 6 * 6 = 36 possible dice combinations.

For the sum to be a 4, there are 3 possible rolls: 1,3 3,1 2,2

So the probability the sum is 4 is 3 * 1/36 = 3/36

For the sum to be an 8, there are 7 possible rolls: 2,6 6,2 3,5 5,3 4,4

So the probability the sum is 8 is 7*1/36 = 7/36

So the probability the sum is 8 or 4 is:

3/36 + 7/36 = 10/36 = 5/18 = 0.278 (3 s.f.)