1. ## Physical Fitness Probability

2. $\mu = 440 \; \mbox{ and } s = 50$
You need that $P(z>x) = 0.1$ , where z is your random variable. Now we need to find x.
So we get, $\mu - 1.28 \cdot s = 440 - 1.28 \cdot 50 = 376 \mbox{ seconds}$