A 646 m long train crosses a man walking at a speed of 4.5 km/h in the opposite direction in 24 seconds. What is the speed (in km/h) of the train?

Given:

A 646 m long train crosses a man walking at a speed of 4.5 km/h in the opposite direction in 24 seconds.

Formula used:

Relative Speed = Speed of Train + Speed of Man

Distance = Speed × Time

Calculation:

Speed of man = 4.5 km/h = m/s = 1.25 m/s

Distance = 646 m

Time = 24 s

⇒ Relative Speed = m/s = 26.9167 m/s

⇒ Speed of Train = Relative Speed - Speed of Man

⇒ Speed of Train = 26.9167 - 1.25 = 25.6667 m/s

Convert speed into km/h:

⇒ Speed of Train = 25.6667 × 18/5 = 92.4 km/h

∴ The correct answer is option 1.