Two trains are moving in opposite directions at 60 km-hr and 90 km-hr. Their lengths are 1.10 km and 0.9 km respectively. What is the time taken by the slower train to cross the faster train in seconds?

Answer: 48 seconds
Explanation

Speed of the two trains: 60 km/hr and 90 km/hr

If train cross each other, then effective speed = 60 + 90 = 150 km/hr

Length of first train = 1.10 km or 1100 m

Length of second train = 0.9 km or = 900 m

formula

Speed = Distance/Time

150 × (5/18) = 2000/Time

125/3 = 2000/Time

Time = 2000 × (3/125)

∴ Time = 48 seconds.

Relative speed = 60 + 90 = 150 km/hr. = 150 x 5/18 = 125/3 m/sec. Distance covered = 1.10 + 0.9 = 2 km = 2000 m. Required time = 2000 x 3/125 = 48 sec.

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