A train overtakes two persons who are walking in the same direction to that of the train at 2 kmph and
4 kmph and passes them completely in 9 and 10 seconds respectively. What is the length of the train?
Choose the correct choice from the following answers.
A) 62 m B) 54 m C) 50 m D) 55 m E) 56 m

Rationale: explanation : let x is the length of the train in meter and v is its speed in kmph x / 9 = ( v - 2 ) ( 10 / 36 ) - - - ( 1 ) x / 10 = ( v - 4 ) ( 10 / 36 ) - - - ( 2 ) dividing equation 1 with equation 2 10 / 9 = ( v - 2 ) / ( v - 4 ) = > 10 v - 40 = 9 v - 18 = > v = 22 substituting in equation 1 , x / 9 = 200 / 36 = > x = 9 × 200 / 36 = 50 m answer : option c
Answer: C