A train X travelling at 72 km/h crosses another train Y travelling at 63 km/h (in opposite direction) in 18 seconds. If the length of train Y is two-third the length of X, then length of train X is:
Answer & explanation
Correct answer: option 3
Relative speed = 72 + 63 = 135 km/h
135 km/h = 135 × \(\frac{5}{18}\) = 37.5 m/sec
Total distance = 37.5 × 18 = 675 m
According to question ,
Let length of train X = 3X
Then Length of train Y = 2X
3X + 2X = 675 m
5X = 675 m
X = 135 m
So , Length of train X = 3 × 135 = 405 m