Multiple choice

The ratio of speed of a motor boat to that of the current of water is 36 : 5. The boat goes along with the current in 5 hours 10 minutes. It will come back in

  1. 5 hr 50 min

  2. 6 hr

  3. 6 hr 50 min

  4. 12 hr 10 min
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Ratio of boat speed (b) to current (c) = 36:5. Downstream speed = 41 units, upstream = 31 units. Time downstream = 5 hr 10 min = 310 min. Distance = 41 * 310. Time upstream = (41 * 310) / 31 = 410 min = 6 hr 50 min.

AI explanation

Let the speed of the motor boat be 36x and the speed of the current be 5x. The downstream speed is 41x and the upstream speed is 31x. Since distance is constant, time is inversely proportional to speed, making the return time equal to (41/31) multiplied by 5 hours 10 minutes. This results in a return time of 6 hours 50 minutes.

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