Question
The speed ratio of train A to train B is 3:2, and both
trains are of equal length. Train A takes x seconds to cross train B when they are moving in the same direction and y seconds when they are moving in opposite directions. If the sum of x and y is 108 seconds, what is the value of (x – y)?Solution
Speed of train A = 3b Speed of train B = 2b Length of train A = B = a 2a = (5b) * 5/18 * y 36a = 25by ------- (1) 2a = b * 5/18 * x 36a = 5bx ------ (2) From (1) and (2) 25by = 5bx 5y = x x + y = 108 6y = 108 y = 18 seconds x = 90 seconds Required difference = 90 – 18 = 72 seconds
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