Multiple choice

Two trains A and B are moving in same direction with the speeds of 108 km/hr and 72 km/hr, respectively. In train B, a passenger starts walking from the front towards the rear end of the train with a speed of 9 km/hr. Assume that at the point he starts walking, the fronts of both the trains are in line with each other. If the length of train A is 125 m and that of train B is 180 m, then in how much time will train A completely cross the passenger in train B?

  1. 8 s

  2. 10 s

  3. 11 s

  4. 12 s

  5. 15 s
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Relative speed of passenger to train A: Train A speed = 30 m/s. Train B speed = 20 m/s. Passenger speed relative to ground = 20 - 2.5 = 17.5 m/s. Relative speed of A to passenger = 30 - 17.5 = 12.5 m/s. Time = Distance / Speed = 125 / 12.5 = 10 s.

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