Multiple choice

The speed of a boat in still water is 10 km/hr. It covers (upstream) a distance of 45 km in 6 hours. The speed (in km/hr.) of the stream is:

  1. 2.5 km/hr.

  2. 3 km/hr.

  3. 3.5 km/hr.

  4. 4 km/hr.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The boat's upstream speed = distance/time = 45/6 = 7.5 km/hr. Upstream speed = boat speed in still water - stream speed. Therefore, stream speed = 10 - 7.5 = 2.5 km/hr. The stream's current slows down the boat by 2.5 km/hr when going upstream. Option A is correct.

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