Correct Answer - Option 3 : 12 hr
Given
A man can swim 3 km/hr in still water. If the velocity of the stream is 2 km/hr, the time is taken by him to swim to a place 10 km upstream and back
Concept used
Boat and stream
Calculation
Let the speed of man in still water be x km/hr = 3 km/hr
Velocity of stream = y km/hr = 2 km/hr
Upstream = (x - y) km/hr
Upstream = (3 - 2) km/hr
Upstream = 1 km/hr
Time = Distance / Speed
Time = 10 hours
Downstream = (x + y) km/hr
Downstream = (3 + 2) km/hr
Downstream = 5 km/hr
Time = 10/5
Time = 2 hours
Total time = 10 + 2
Total time = 12 hours.
