Correct Answer - Option 2 : 198 km/h
Length of train = 300 m
Time is taken by train to pass a pole = 15 seconds
Time taken to cross another train of the same length = 8 seconds
Calculations:
Speed of the 1st train = 300/15 = 20 m/s
Let the speed of 2nd train be x
Relative speed = (20 + x) m/s
Length of 1st train + length of 2nd train = 300 + 300 = 600 m
In the second scenario the equation is
⇒ 600/(20 + x) = 8
⇒ 600 = 160 + 8x
⇒ 600 – 160 = 8x
⇒ 440 = 8x
⇒ x = 55 m/s
∴ Speed of the train = 55 × 18/5 = 198 km/h.
The speed of the train is 198 km/h.