Top Ten Percent
1. **State the problem:** We are given a normal distribution of finishing times with mean $\mu = 69.8$ seconds and standard deviation $\sigma = 1.3$ seconds. We want to find the slowest time $x$ such that the RP men's team ranks in the top 10% of all times. This means their time must be less than or equal to the 10th percentile of the distribution.
2. **Understand the percentile:** The top 10% fastest times correspond to the lowest 10% of the finishing times because lower times are better. So we need to find the 10th percentile value $x$ where $P(X \leq x) = 0.10$.
3. **Find the z-score for the 10th percentile:** Using the standard normal distribution table or a calculator, the z-score $z$ for the 10th percentile is approximately $z = -1.28$.
4. **Use the z-score formula:**
$$
z = \frac{x - \mu}{\sigma}
$$
Substitute $z = -1.28$, $\mu = 69.8$, and $\sigma = 1.3$:
$$
-1.28 = \frac{x - 69.8}{1.3}
$$
5. **Solve for $x$:**
$$
x - 69.8 = -1.28 \times 1.3 = -1.664
$$
$$
x = 69.8 - 1.664 = 68.136
$$
6. **Interpretation:** The slowest allowable time to be in the top 10% is approximately $68.14$ seconds.
**Final answer:**
$$\boxed{68.14 \text{ seconds}}$$