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.
Answer & explanation
Correct answer: option 2
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