Could the answer be 5/12?
n(A U B) = n(A) + n(B) - n (A and B)
6/36 + 11/36 - 2/36 = 5/12
Two 6-sided die are rolled.
Find the probability that the first die shows a 2, or the sum of the two die is 6 or 7.
The least we can do is crank out the possible outcomes and start counting.
"First die is 2": .
"Sum is 6 or 7": .
There are 15 desirable outcomes.