Subject
Quantitative Aptitude
Topic
Speed & Distance
A train travelling at 48 kmph completely crosses another train having half its length and travelling in opposite direction at 42 kmph, in 12 seconds. It also passes a railway platform in 45 seconds. The length of the platform is
A train travelling at 48 kmph completely crosses another train having half its length and travelling in opposite direction at 42 kmph, in 12 seconds. It also passes a railway platform in 45 seconds. The length of the platform is
ক)
400 mখ)
450 mগ)
560 mঘ)
600 mExplanation
Let the length of the first train be x metres. Then, the length of the second train is (x/2) metres. Relative speed = (48 + 42) kmph = (90 x (5/18)) m/sec = 25 m/sec. Therefore, (x + (x/2)) / 25 = 12 Or, 3x/2 = 300 or, x = 200. Therefore, Length of first train = 200 m. Let the length of platform be y metres. Speed of the first train = (48 x(5/18)) m/sec = (40/3) m/sec. Therefore, (200 + y) x (3/40) = 45 => 600 + 3y = 1800 => y = 400 m.Related questions
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