jmc

William ran for 75 seconds, which we will have to convert to miles. We know have conversion factors to get from seconds to hours, namely $\frac{1\text{ minute}}{60\text{ seconds}}=1$ and $\frac{1\text{ hour}}{60\text{ minutes}}=1$. We are also given William's running speed, so $\frac{8\text{ miles}}{1\text{ hour}}=1$. Thus, we can find that William ran $$75\text{ seconds}\cdot \frac{1\text{ minute}}{60\text{ seconds}}\cdot \frac{1\text{ hour}}{60\text{ minutes}}\cdot \frac{8\text{ miles}}{1\text{ hour}}=\boxed{\frac{1}{6}}\text{ miles.}$$