Problems on Trains - General Aptitude

Q1:

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

ANS:A - 9

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