Multiple choice

A train of length 100 m crosses another train of length 150 m, running on a parallel track in the opposite direction, in 9 seconds. If the speed of the train having length 150 m is 40 km/hr, then what is the speed (in km/hr) of the other train?

  1. 30

  2. 48

  3. 50

  4. 60
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Total distance = 100 + 150 = 250 m. Time = 9 seconds. Relative speed = 250/9 m/s. Convert to km/hr: (250/9) * (18/5) = 100 km/hr. Since they are in opposite directions, relative speed = v1 + v2. 100 = v1 + 40, so v1 = 60 km/hr.

AI explanation

The total distance covered when the two trains cross each other is the sum of their lengths, which is 100 metres plus 150 metres, equaling 250 metres. Because their relative speed multiplied by the crossing time of 9 seconds equals this distance, their relative speed is 250 divided by 9 metres per second. Converting this to kilometres per hour by multiplying by 18 over 5 gives 100 kilometres per hour, and since the 150 metre train is moving at 40 km/hr, the other train's speed is 100 minus 40, equaling 60 km/hr.

Keep practicing — related questions