2017 · Q35
A 225 m long train is running at a speed of 30 km/hour. How much time does it take to cross a man running at 3 km/hour in the same direction ?
Elementary MathematicsTime, Speed and Distance
- A40 seconds
- B30 seconds
- C25 seconds
- D15 seconds
Explanation
Relative speed = 30 − 3 = 27 km/h = 7.5 m/s. Time to cover 225 m = 225/7.5 = 30 s: option B. Using the train's speed alone wrongly gives 27 s.