csatmedium
A freight train left Delhi for Mumbai at an average speed of 40 km/h. Two hours later, an express train left Delhi for Mumbai, following the freight train on a parallel track at an average speed of 60 km/h. How far from Delhi would the express train meet the freight train ?
- A.480 km
- B.260 km
- C.240 km
- D.120 km
▶ Answer & Explanation
Correct answer: C. 240 km
The freight train has a head start of 2 hours, during which it covers 40 km/h * 2 h = 80 km. The express train travels 20 km/h faster than the freight train (60 km/h - 40 km/h), meaning it closes the 80 km gap at a relative speed of 20 km/h. Therefore, it will take 80 km / 20 km/h = 4 hours for the express train to catch up. In these 4 hours, the express train travels 60 km/h * 4 h = 240 km from Delhi.
Source: UPSC csat 2017