Explanation:
Let the total distance be 150 km. First part = 50 km; Time = 50/20 = 2.5 hours. Remaining part = 100 km; Time = 100/50 = 2 hours. Total distance = 150 km, Total time = 4.5 hours. Average speed = 150 / 4.5 = 1500 / 45 = 34.28 km/h.
A train 120 meters long running at 108 km/h completely passes another train 180 meters long running at 72 km/h in the same direction. How much time do they take to clear each other?
Explanation:
Total distance to be covered = 120 + 180 = 300 meters. Relative speed in same direction = 108 - 72 = 36 km/h = 36 * (5/18) = 10 m/s. Time taken = 300 / 10 = 30 seconds.
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