The length of a river is 21 km. Speed of boat in still water is 5 km/h boat takes 10 hours to go and come back. Find the speed of stream.

1 km/hr 2 km/hr 3 km/hr 4 km/hr

2 km/hr

Let V=  speed of current Speed of boat in downstream = 5 + v Speed of boat in upstream = 5 - v ATQ, \(\frac{21}{5 + v}\) + \(\frac{21}{5 - v}\) = 10 Now check options. V = 2km/hr