The speed of a boat in still water is 4 km/hr and the speed of current is 2 km/hr. If the time taken to reach a certain distance upstream is 9 hours, find the time it will take to go same distance downstream?
Correct Answer: 3 hrs
Explanation:
Upstream distance = (4 - 2) x 9 = 18 km
∴ Required time = 18/(4 + 2) = 3 hrs.
