Multiple choice

Speed of boat A is 50% more than speed of boat B in still water, if both boats start in a lake at same time from point P downstream at the same time and reach point Q, which is 72 km away from point P at the same time. Boat A lost 120 minutes during journey because of engine did not work properly, find time taken by boat A to cover given distance in upstream with the 50% of its speed?

  1. 8 hours

  2. 10 hours

  3. 6 hours

  4. 12 hours

  5. 14 hours
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Let B's speed = 2x, then A's speed = 3x (50% more). Distance = 72 km. B's time downstream = 72/3x = 24/x hours. A loses 120 minutes (2 hours), so A's effective time = 24/x - 2 = 72/3x. For upstream at 50% speed: A's speed = 1.5x, time = 72/1.5x = 48/x. From B's time: 24/x = T, so upstream time = 48/x = 2T. Both reach together, so T = 4 hours. Upstream time = 8 hours. Option A matches.

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