Train 'P' can cross a pole in 8 seconds and a 160 metres

Solution

Let the length and the speed of the train 'P' be 'x' metres and 's' m/s.
ATQ,
(x/s) = 8
So, 'x' = 8s.........(i)
Also, {(x + 160) ÷ s} = 12
Or, 8s + 160 = 12s [from equation (i)]
Or, 160 = (12s - 8s)
Or, 's' = (160/4) = 40
Length of train 'P' = (8 × 40) = 320 metres
So, length of train 'Q' = (320 × 0.60) = 192 metres
Let the speed of train 'Q' be 'q' m/s.
ATQ,
(320 + 192) ÷ (q - 40) = 16
Or, 512 = 16 × (q - 40)
Or, (q - 40) = 32
So, 'q' = 32 + 40 = 72
Therefore, speed of train 'Q' = 72 m/s