Correct option is A
Given:
Length of two trains = 400m and 720m
Speed of train = 64km/hr and 80km/hr respectively
Formula Used:
Time
Solution:
Relative speed of two trains = 64 + 80 = 144km/hr
Speed in metre per second = = 40m/sec
If man is sitting in first train distance = length of second train = 720m
Time taken = = 18seconds