If a pair of standard dice are rolled, what is the probability that one die shows a 6 but not both of them?
There are two possibilities:
-- either the first die has a six and the second one doesn't: (1/6) x (5/6) = 5/36
-- or the first dies doen't have a six and the second one does: (5/6) x (1/6) = 5/36
To find the total probability, add these two probabilities together: 5/36 + 5/36 = 10/36