A train, travelling at a uniform speed for 360 km, would have taken 48 mins less to travel the same distance, if its peed were 5 km/hr more. Find the original speed of the train.


Let the original speed of the train be x km/hr

Then, the increased speed of the train = (x + 5) km/hr


According to question,


[* ]



[5(360x + 1800) – (360x)] = 4x (x + 5)


4x2 + 20x – 9000 = 0


x2 + 5x – 2250 = 0


By using the quadratic formula,






The original speed of the train is 45 km/hr. (* Speed cannot be negative)


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