Multiple choice

A boat can travel with a speed of $22$ km/hr in still water. If the speed of the stream is $8$ km per hr, find time taken by it to go $135$ km downstream.

  1. $ 9\cfrac{1}{2} $ hours
  2. $ 5\cfrac{7}{2} $ hours
  3. $ 8\cfrac{4}{5} $ hours
  4. $ 4\cfrac{1}{2} $ hours
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D Correct answer
Explanation

Downstream speed = speed of boat + speed of stream = 22 + 8 = 30 km/hr. Time = Distance / Speed = 135 / 30 = 4.5 hours, which is 4 and 1/2 hours.

AI explanation

First, find the downstream speed by adding the speed of the boat in still water to the speed of the stream, giving 22 km/hr plus 8 km/hr, which equals 30 km/hr. Using the formula time equals distance divided by speed, divide the downstream distance by this speed: 135 km divided by 30 km/hr equals 4.5 hours. This result is equivalent to 4 1/2 hours.

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