Correct Answer - Option 2 : 58.5 km/hr
Given:
Length of trains = 200 m and 250 m
Time taken to cross if travelling in opposite direction = 18 seconds
Time taken to cross if travelling in same direction = 60 seconds
Concept used:
When to bodies are moving in the opposite direction, the relative speed is calculated by adding the speed of both the bodies.
When two bodies are moving in the same direction, the relative speed is computed by their difference
Calculation:
Let speeds of both trains be x m/s and y m/s
Now, according to question,
⇒ x + y = 450/18 = 25 m/s ----(i)
⇒ x – y = 450/60 = 7.5 m/s ----(ii)
Adding equation (i) and (ii)
2x = 32.5
⇒ x = 16.25 m/s = 16.25 × (18/5) km/hr
⇒ 58.5 km/hr
∴ The speed of faster train is 58.5 km/hr