Two trains having lengths of 410 m and 440 m are running at speeds of 60 km/h and 70 km/h, respectively, in the same direction. The time taken (in minutes) by the faster train, coming from behind, to completely cross the other train is:
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 5.1
Length of trains = 410 m and 440 m
Total distance = 410 + 440 = 850 m
Speeds = 60 km/h and 70 km/h
Relative speed = 70 − 60 = 10 km/h = 10 × 5/18 = 25/9 m/s
Time = distance ÷ speed = 850 ÷ (25/9) = 850 × 9/25 = (850 ÷ 25) × 9 = 34 × 9 = 306 s
306 ÷ 60 = 5.1 minutes