Answer:
P = 0.075 P = 7.5%
Explanation:
We pretty much look for the probability that the player fails the first attempt and also fails the second attempt.
We know for a fact that the probability that the quarterback fails the first attempt is:
p(1) = 0.5
and we know that the probability that the quarterback fails the second attempt after failing the first is:
p(2/1) = 0.15
Then the probability of failure of both attempts is:
P(2/1) = p(1 and 2) / p(1)
p(1 and 2) = P(1) * P(1/2)
p(1 and 2) = 0.5 * 0.15
and that is
p(1 and 2) = 0.075
you probably didn't want the nerdy stuff but oh well