13. Laura owns two dice. One of them is a regular game die, with faces numbered from 1 to 6. The other is a special die, which has two faces with the number 3, one face with the number 4, and three faces with the number 6. By rolling both dice together, what is the probability that the sum of the two numbers rolled is equal to 8?
(A) $2 / 9$
(B) $1 / 6$
(C) $1 / 9$
(D) $1 / 12$
(E) $1 / 8$
(13) The correct answer is $(B)$.

Regardless of the score achieved by the special die (3, 4, or 6), there is exactly 1 score out of 6 on the regular die for which the sum of the two scores is 8. The probability that the sum is 8 is therefore $1 / 6$.

Question proposed by Sandro Campigotto.