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: Choose the correct choice from the following answers:
A) 45m B) 50m C) 54m D) 72m E) 70m
Explanation:   2 kmph =	(	2 x5/18)m/sec =	5/9m/sec.   4 kmph =(4x5/18)m/sec =10/9m/sec.   Let the length of the train be x metres and its speed by y m/sec.   Then,	(x/y-5/9)=9and(x/y -	10/9)=10.   9y - 5 = x and 10(9y - 10) = 9x   =&gt; 9y - x = 5 and 90y - 9x = 100.   On solving, we get: x = 50.   Therefore Length of the train is 50 m.   ANSWER IS 50m
<result>B</result>
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: