A train overtakes two persons who are walking in the same direction in which the train is going, at the rate of 2 kmph and 4 kmph and passes them completely in 9 and 10 seconds respectively.The length of the train is:
Answers.
A) 35M
B) 45M
C) 55M
D) 50M
E) 40M
2 kmph = ( 2 x 5/18) m/sec = 5/9 m/sec.   4 kmph = ( 4 x 5/18)m/sec = 10/9 m/sec.   Let the length of the train be x metres and its speed by y m/sec.   Then, ( x / y-5) = 9 and x / (y-10/ 9) = 10.   Therefore 9y - 5 = x and 10(9y - 10) = 9x   =9y - x = 5 and 90y - 9x = 100.   On solving, we get: x = 50 ANSWER : 50M
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A train overtakes two persons who are walking in the same direction in which the train is going, at the rate of 2 kmph and 4 kmph and passes them completely in 9 and 10 seconds respectively.The length of the train is: