Multiple choice

If 2 hours and 30 minutes is the time taken to row a boat 15 km downstream and 1 hour and 30 minutes is the time taken to cover a distance of 6 km upstream, then find the speed (in km/hr) of the current.

  1. 5 km/hr

  2. 2 km/hr

  3. 4 km/hr

  4. 1 km/hr

  5. 2.5 km/hr
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Downstream speed (D) = 15 km / 2.5 h = 6 km/h. Upstream speed (U) = 6 km / 1.5 h = 4 km/h. Speed of current = (D - U) / 2 = (6 - 4) / 2 = 1 km/h.

AI explanation

Using the formula Speed = Distance / Time, the downstream speed is 15 / 2.5 = 6 km/hr and the upstream speed is 6 / 1.5 = 4 km/hr. The speed of the current is given by half the difference of the downstream and upstream speeds, which is (6 - 4) / 2 = 1 km/hr. The speed of the current is 1 km/hr.

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