A train B speeding with 120 kmph crosses another train C running in the same…

2025

A train B speeding with 120 kmph crosses another train C running in the same direction, in 2 minutes. If the lengths of the trains B and C be 100 m and 200 m respectively, what is the speed (in kmph) of the train C?

  1. A.

    111

  2. B.

    123

  3. C.

    127

  4. D.

    129

Attempted by 17 students.

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Correct answer: A

Answer: 111 km/h

  1. Convert the speed of train B to m/s: 120 km/h = 120 × (5/18) = 100/3 m/s.

  2. Let speed of train C be v m/s. Since both trains move in the same direction, relative speed = (100/3 − v) m/s.

  3. Distance to be covered for crossing = length of B + length of C = 100 + 200 = 300 m. Time = 2 minutes = 120 s.

  4. Use time = distance / relative speed: 300 / (100/3 − v) = 120. So 100/3 − v = 300/120 = 5/2.

  5. Solve for v: v = 100/3 − 5/2 = (200 − 15)/6 = 185/6 m/s ≈ 30.833... m/s.

  6. Convert v to km/h: v = (185/6) × (18/5) = 111 km/h.

Therefore, the speed of train C is 111 km/h.

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