The speed of a boat in still water is 8km/h. It travels upstream for a distance of 1.5km and returns(downstream) to the starting point. If the whole trip takes 2/5 hours, find the speed of the stream flow.

Answer 1

Since time = distance/speed,

1.5/(8-s) + 1.5/(8+s) = 0.4
s = 2

Answer 2

7.1km/hr