Multiple choice

A boat can cover 18 km downstream in 2 hours. If the speed of stream is 2 km/hr, then what is the speed of the boat in upstream?

  1. 8 km/hr

  2. 5 km/hr

  3. 6 km/hr

  4. 7 km/hr
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Downstream speed = 18 km / 2 hr = 9 km/hr. Downstream speed = boat speed + stream speed. 9 = boat + 2, so boat = 7 km/hr. Upstream speed = boat - stream = 7 - 2 = 5 km/hr.

AI explanation

The downstream speed is 18 km divided by 2 hours, which equals 9 km/hr. Using the formula Boat Speed = Downstream Speed - Stream Speed, the speed of the boat in still water is 9 - 2 = 7 km/hr. Using the formula for upstream speed, Upstream Speed = Boat Speed - Stream Speed, the result is 7 - 2 = 5 km/hr.

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