Multiple choice

A man can row a boat in still water at a speed of 5 m/s. He covers a stretch of 200 m in a river downstream during high and low tides in 10 sec and 25 sec respectively. What is the ratio of the speed (in m/s) of the water flowing in the river during high and low tides?

  1. 5 : 3

  2. 5 : 1

  3. 3 : 2

  4. 4 : 3

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Downstream speed = boat speed + current speed. In high tide: 200m in 10s = 20 m/s. Current speed = 20-5 = 15 m/s. In low tide: 200m in 25s = 8 m/s. Current speed = 8-5 = 3 m/s. Ratio of current speeds = 15:3 = 5:1.