Question

What is the probability of the sum of two fair dice equals a prime number when rolled once?

Answer 1

So we are looking for a sum of

2,3,5,7,or 11
number of ways for 2 is 1
number of ways for 3 is 2
number of ways for 5 is 4
number of ways for 7 is 6
number of ways for 11 is 2

so prob for a prime = (1+2+4+6+2)/36 = 5/12