A man takes 15 minutes to row 16 km downstream, which is 25% less than the time he takes to row the same distance upstream. How many kilometres can the man row in an hour in still water? (Rounded off to nearest whole number)
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 56
Given that
A man row 16 km downstream in 15 minutes
A man row 16 km upstream in (15 × 100/25) = 20 minutes
Let speed of current be x and a man's speed = y
According to the question
The downstream speed of a man = x + y = (16/15) × 60 = 64 km/h....(1
The upstream speed of a man = y - x = (16/(1/3)) = 48 km/h....(2
Equation 1 + Equation 2
2y = 112
y = 56 km/h
So, the man covered distance in still water in an hour = 56 km