A 108-metre-long train moving at 50 km/hr crosses a 112-metre-long train coming from the opposite direction in 6 seconds. The speed of the second train is:

A48 km/hr

B54 km/hr

C66 km/hr

D82 km/hr ✓ Correct

Correct answer: (D) 82 km/hr

Explanation

The second train's speed is 82 km/hr.

Together they cover 108 + 112 = 220 m in 6 seconds.

Relative speed = 220 / 6 m/s = (220/6) x 18/5 = 132 km/hr.

The trains move opposite, so relative speed = sum of speeds = 50 + v.

50 + v = 132, so v = 82 km/hr.

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