1.  Two trains 140 m and 160 m long run at the speed of 60 km/hr and 40 km/hr respectively in opposite directions on parallel tracks. The time (in seconds) which they take to cross each other, is:
A. 9
B. 9.6
C. 10
D. 10.8

Answer: Option D

Explanation:

Relative speed = (60 + 40) km/hr

= 100 x 5 m/sec = 250 m/sec.
18 9

Distance covered in crossing each other = (140 + 160) m = 300 m.

Required time

= 300 x 9 sec = 54 sec = 10.8 sec.
250 5