On a circular track, A completes a lap in 5 minutes and B in 8 minutes, running the same way from the same point. How many times does A pass B in the first hour?

Explanation

1. 01

   A gains $\frac{1}{5} - \frac{1}{8} = \frac{3}{40}$ of a lap on B every minute, so a full lap every $\frac{40}{3} \approx 13.3$ minutes.

2. 02

   Each full lap gained is one pass. In 60 minutes A gains $60 \times \frac{3}{40} = 4.5$ laps: 4 passes, the fifth coming only after about 66.7 minutes.