Question

A boat moves at 15 km/h in still water and the stream flows at 3 km/h. Find its downstream and upstream speeds.

Solution

1. Downstream speed = still-water speed + stream speed.
2. Downstream speed = 15 + 3 = 18 km/h.
3. Upstream speed = still-water speed - stream speed = 15 - 3 = 12 km/h.
4. Therefore, the downstream speed is 18 km/h and the upstream speed is 12 km/h.