Multiple choice

Two trains A and B have lengths equal to 120 m and 24 m, respectively. Train A passes train B in 12 sec. If train B travelling in opposite direction has a speed of 4 m/sec, find the speed of the train A (in km/hr).

  1. 25.3

  2. 26 .67

  3. 28.8

  4. 30

  5. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Total distance = 120 + 24 = 144 m. Relative speed = 144 / 12 = 12 m/s. Since they are in opposite directions, relative speed = speed A + speed B. 12 = speed A + 4, so speed A = 8 m/s. 8 m/s = 8 * (18/5) = 28.8 km/h.

AI explanation

The total distance the trains need to cover to cross each other is 120 m plus 24 m, totaling 144 m. Their relative speed is distance divided by time, so 144 m divided by 12 sec gives a relative speed of 12 m/s. Since train B travels at 4 m/s, the speed of train A is 12 m/s minus 4 m/s, which is 8 m/s. Multiplying by 18/5 converts this to 28.8 km/hr.

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