A pair of fair dice is rolled and the numbers noted. What is the probability that the sum is 8 given that at least one die shows a 3?

Question

I have tried to get this question right for days. I honestly hate probabilities but anyway. Can someone explain to me how to solve this? Thanks a bunch!

Answer 1

Well if at least 1 die shows a 3 the possible rolls are

3 3

3 1

3 2

3 4

3 5

3 6

1 3

2 3

4 3

5 3

6 3

There are 11 possible ways this can happen, of these 2 have a sum of 8, so it is 2/11