Multiple choice

A boat takes 6 hours to travel from A to B upstream. If the river current flows at the rate of 2 kmph, how long will the boat take to travel from B to A (downstream), the distance being 36 km?

  1. 2.6 hours

  2. 4 hours

  3. 4.8 hours

  4. 3.6 hours
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Upstream speed = 36 / 6 = 6 kmph. Boat speed - Stream speed = 6. Boat speed - 2 = 6, so Boat speed = 8 kmph. Downstream speed = 8 + 2 = 10 kmph. Time = 36 / 10 = 3.6 hours.

AI explanation

The upstream speed is the total distance of 36 km divided by the time of 6 hours, which gives a speed of 6 kmph. Since the upstream speed equals the boat's speed in still water minus the river current, the boat's speed in still water is 6 plus 2, or 8 kmph. The downstream speed becomes 8 plus 2, which equals 10 kmph, making the downstream travel time 36 km divided by 10 kmph, resulting in 3.6 hours.

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