1.  A train 108 m long moving at a speed of 50 km/hr crosses a train 112 m long coming from opposite direction in 6 seconds. The speed of the second train is:
A. 48 km/hr
B. 54 km/hr
C. 66 km/hr
D. 82 km/hr

Answer: Option D

Explanation:

Let the speed of the second train be x km/hr.

Relative speed = (x + 50) km/hr
= [ (x + 50) x 5 ] m/sec
18
= [ 250 + 5x ] m/sec.
18

Distance covered = (108 + 112) = 220 m.

Therefore 220 = 6
( 250 + 5x (
18

=> 250 + 5x = 660

=> x = 82 km/hr.