There are two docks, dock A and Dock B, on a large lake. The distance between the two docks is 72.5 km. Dock B is directly east of dock A. One day, a steam boat leaves from dock A at noon, and heads eastward. At the same time, a large ferry leaves from dock B, and heads southward. The steam boat travels with a speed of 20 km/hr. The speed of the ferry is 8 km/hr.
The visibility on the lake is 20 miles that day. Would passengers on one boat ever have a chance to see the other boat? If yes, how long is their “window of opportunity”?