Multiple choice

A man covers a distance of 1440 km in 36 hours down the stream. If the speed of the current is (\frac{1}{7}) of the speed of the boat's speed. Find the speed of the stream.

  1. 40 km/hr

  2. 12 km/hr

  3. 7.5 km/hr

  4. 5 km/hr

  5. 2.5 km/hr

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

Downstream speed = 1440/36 = 40 km/hr. Boat speed + stream speed = 40. Given stream = boat/7, let boat = 7x, stream = x. 7x + x = 40, so 8x = 40, x = 5. Stream speed is 5 km/hr. Option D matches.