Question
A train would take 20 seconds to cross a stationary
pole. If the train was 200m shorter, it would have taken 10 seconds less. Find the speed of the train.Solution
Let the original length of the train =  x m ∴ Speed of the original train = x/20 m/s ∴ Length of the shorter train = x-200 ∴ speed of the shorter train = (x-200)/10 m/s Since, both the train are same their speed are also same ∴ (x )/20 = (x-200)/10 ⟹ 10 x = 20 x- 4,000 10 x =4,000  x = 400 ∴ Speed = x/20 =400/20 = 20m/s
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