Previous Year Questions

Let the lengths of the trains be 'a' m and 'b' m respectively.

Since, the trains are approaching in the first case,

Relative speed = 20 + 30 = 50 m/s.

Distance covered = (a + b) m.

Given, time taken = 10 s

∴ a + b = 50*10 = 500..(i)

Length of the third train = (a - b) m

∴ Distance travelled by the third train while crossing the man = (a - b + 100) m

∴ Relative speed = 43 - 3 = 40 m/s

Given, Time taken = 5 s

∴ a - b + 100 = 40*5

=> a - b = 100..(ii)

Adding the two equations, we get

a = 300 m and b = 200 m

∴ Ratio of the length of the trains = 300:200 = 3:2