Question
A train with 10 compartments of equal length takes 20
seconds to cross a pole and 28 seconds to cross a 160-metre-long platform. If 4 compartments of the train are removed, then how long would it take to cross a pole?Solution
Let the original length of the train = βdβ metres
Then, distance covered by the train in 20 seconds = βdβ metres
Distance covered by the train in 28 seconds = (d + 160) metres
So, distance covered by the train in (28 β 20) = 8 seconds = (d + 160 β d) = 160 metres
So, speed of the train = 160 Γ· 8 = 20 m/s
So, original length of the train = 20 Γ 20 = 400 metres
After removing 4 compartments, length of the train = 400 Γ (6/10) = 240 metres
So, required time taken = 240 Γ· 20 = 12 seconds
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