Multiple choice

A person rows 13 km upstream and 28 km downstream, taking 5 hours each time. Find the velocity (in km/hr) of the current.

  1. 1.5

  2. 1.2

  3. 1.6

  4. 1.75

  5. 2.0
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A Correct answer
Explanation

Upstream speed = 13/5 = 2.6. Downstream speed = 28/5 = 5.6. Current speed = (Downstream - Upstream) / 2 = (5.6 - 2.6) / 2 = 3 / 2 = 1.5.

AI explanation

The upstream speed is 13 km divided by 5 hours, giving 2.6 km/hr, and the downstream speed is 28 km divided by 5 hours, giving 5.6 km/hr. The speed of the boat in still water is the average of these two speeds, which is (2.6 + 5.6)/2 = 4.1 km/hr. The velocity of the current is the difference between the downstream speed and the still water speed, which is 5.6 - 4.1 = 1.5 km/hr.

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