Train A crosses train B running in the same direction in 67.5 seconds and the speed of train A and B is in the ratio of 3:2

Train A crosses train B running in the same direction in 67.5 seconds and the speed of train A and B is in the ratio of 3:2 respectively. If the difference between the speed of train A and B is 24 kmph, then what is the time taken by train A to cross train B running in the opposite direction?

a)            14.4 seconds

b)            18 seconds

c)            13.5 seconds

d)            12.8 seconds

e)            Cannot be determined

Sol:

Speed of train A = 3/1 * 24 = 72 kmph

Speed of train B = 2/1 * 24 = 48 kmph

Length of train A = x

Length of train B = y

x + y = 24 * 5/18 * 67.5

x + y = 450

Required time = 450/((5 * 24) * 5/18) = 13.5 seconds