Multiple choice

A train 150 m long, passes a 150 m. long platform in 30 seconds and another train of the same length travelling in the opposite direction in 12 sec. The speed of the second train is

  1. 45 km./hr

  2. 48 km./hr

  3. 52 km./hr

  4. 54 km./hr
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Train 1 crosses 150m platform in 30 sec: (150+150)/30 = 10 m/s = 36 km/hr. Let train 2 speed = v km/hr = (5v/18) m/s. Relative speed when crossing: (10 + 5v/18) m/s. Time = 12 sec for (150+150) = 300m. So 300/12 = 10 + 5v/18. 25 = 10 + 5v/18. 15 = 5v/18. v = 54 km/hr. Answer D is correct.

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