Two trains are running on parallel tracks in the same direction at the speed of 80 km/h and 90 km/h, respectively. The trains crossed each other in 3 minutes. If the length of one train is 230 m, then what is the length (in m ) of the other train?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 270
Given:
Speed of two trains are 80 km/hr and 90 km/hr.
Time = 3 minutes
Concept Used:
Time = Distance/speed
Relative speed = When two bodies move in the same direction then their relative speed of them will be different from the individual speed
Explanation:
The relative speed of the trains = 90 - 80 = 10 km/h
Speed in m/sec = 10 × (5/18) = 25/9
Let the length of the other train be x m.
[(230 + x)/(25/9)] = 180
⇒ (230 + x) = 180 × (25/9)
⇒ 230 + x = 500
⇒ x = 270
Hence the length of the other train is 270 m.