Question

A person can row a distance of one kilometre upstream in 10 min and downstream in four min. What is the speed of the stream?

Answer 1

1 km in 10min or 1/6hr.

So, speed here, is 6km/hr.

6km/hr = Vs-Vr (eq@1)

Vs- speed in still water.

Vr- speed in moving water.

So, similarly

4min or 1/15hr,

15km/hr = Vs+Vr (eq@2)

So. From (eq@1 and eq@2)

Vs=10.5km/hr.

Vr=4.5km/hr.