Two trains 200 meters and 150 meters long are running on parallel rails in the same direction at speed of 40 km/hr and 45 km/hr respectively. Time taken by the faster train to cross the slowed train will be:

Answer: Option D

Relative speed = (45 - 40) km/hr = 5 km/hr
= $$\left(5\times \frac{5}{18}\right)$$  m/sec
= $$\frac{25}{18}$$ m/sec
Total distance covered = Sum of lengths of trains = (200 + 150) m = 350 m
∴ Time taken
= $$\left(350\times \frac{18}{25}\right)$$   sec
= 252 seconds