Two trains of equal length travelling in opposite directions at 78 km/h & 117 km/h cross each other in 12 seconds . In how much time (in seconds) does the first train cross a platform of length 455 meter ?
Answer & explanation
Correct answer: option 4
Let the length of each train = x
Distance = Speed × Time
To convert km/hr into m/sec.
A km/hr × \(\frac{5}{18}\) = B m/sec
As the trains travel in opposite direction.
So, their relative speed = ( 78 + 117 ) km/hr
2x = (78 + 117) × \(\frac{5}{18}\) × 12
2x = 650 m
x = 325 m
length of ( Platform + Train ) = Speed × Time
(455 + 325) = 78 × \(\frac{5}{18}\) × T
T = 36 seconds