Two buses each 3125 m long are running in opposite directions on parallel roads. Their speeds are 40 km/hr and 35 km/hr respectively. Find the time taken by the slower bus to pass the driver of the faster one?
Choose the correct choice from the following options.
A) 50 sec  B) 66 sec  C) 48 sec  D) 55 sec  E) 45 sec

Rationale: relative speed = 40 + 35 = 75 km / hr . 75 * 5 / 18 = 125 / 6 m / sec . distance covered = 3125 + 3125 = 6250 m . required time = 6250 * 6 / 125 = 50 sec . answer : a
Answer: A