Question

Brian rolls 2 fair dice and adds the results from each. Work out the probability of getting a total that is prime. Answer THIS PLEASE I AM SO CONFUSED

Answer 1

5/12 or 15/36

Explanation:

Since he rolls two dice, he has a total probability of 6 times 6 = 36. The pairs, that he could add up to primes are (1,1), (2,1) * 2 (since he can get 1,2 as well), (1,4) * 2, (2,3) * 2, (3,4) * 2, (5, 2) * 2, (6,1) * 2, (5, 6) * 2. This is 1 + 2 + 2 + 2 + 2 + 2 + 2 + 2, which is equal to 15. This is a total of 15/36 possible ways, which is also equal to 5/12.