Multiple choice

The speed of a boat in still water is 50 km/hr. It covers a distance of 500 km upstream in 20 hours. What is the speed (in km/hr) of the stream?

  1. 20

  2. 25

  3. 45

  4. 30
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Boat speed in still water = 50 km/hr. Upstream speed = 500/20 = 25 km/hr. Let stream speed = s. Upstream speed = boat speed - stream speed, so 25 = 50 - s, giving s = 25 km/hr. This confirms option B. Stream speed is the difference between still water speed and upstream speed.

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