Question
Train ‘A’ running with a speed of 72 km/hr can cross
a standing goods train of 4 times its length in 21 seconds. Find the time taken by 350 metres long train ‘B’ which is coming from opposite direction of train ‘A’, with a speed of 10 m/s, to cross train ‘A’.Solution
Let the length of train ‘A’ be ‘x’ metres Therefore, length of the goods train = ‘4x’ metres Speed of train ‘A’ = 72 × (5/18) = 20 m/s According to the question, 4x + x = 20 × 21 => 5x = 420 => x = 84 Therefore, time taken by train ‘B’ to cross train ‘A’ = {(84 + 350)/(21 + 10)} = 14 seconds
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