Question 15
Alberto and Barbara play with a dice. After a while they realize that the die is rigged, and that the number $1$ comes up more frequently than the other numbers $5$ (which instead remain equally probable). They then decide that when $1$ comes out, that roll is canceled and they roll again. If you continue to roll the dice until you get $2$ valid rolls, what is the probability that the sum of the $2$ valid numbers rolled is $8$?
(A) $\frac{3}{25}$
(B) $\frac{1}{6}$
(C) $\frac{1}{5}$
(D) $\frac{6}{25}$
(E) $\frac{1}{4}$.
(A) $\frac{3}{25}$
(B) $\frac{1}{6}$
(C) $\frac{1}{5}$
(D) $\frac{6}{25}$
(E) $\frac{1}{4}$.