Two trains of equal are running on parallel lines in the same direction at 50 km/hr and 36 km/hr. The faster train passes the slower train in 36 sec. The length of each train is? Choose the correct option.
A) 70 m  B) 72 m  C) 80 m  D) 82 m  E) 84 m

Rationale: "let the length of each train be x m . then , distance covered = 2 x m . relative speed = 50 - 36 = 14 km / hr . = 14 * 5 / 18 = 35 / 9 m / sec . 2 x / 36 = 35 / 9 = > x = 70 . answer : a"
Answer: A