A man can row a distance of 6 km in 1 hour in still water. He can row the same distance in 45 minutes with the current. Find the total time taken by him to row a distance of 16 km with the current and to return to the starting point.
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 6 hours.
Speed = Distance/time
Speed of man in still water = 6/1 = 6 km/h
45 minutes = 3/4 hours
Downstream speed = 6/(3/4) = 8 km/h
Speed of current = Downstream speed - Speed of man = 8 - 6 = 2 km/h
Upstream speed = Speed of man - Speed of current = 6 - 2 = 4 km/h
Time required to row 16 km downstream and 16 km upstream = (16/8) + (16/4) = 2 + 4 = 6 hours