A 270 metres long train running at the speed of 120 kmph crosses another train running in opposite direction at the speed of 80 kmph in 9 seconds. What is the length of the other train?  Choose the correct choice from the following answers:
A) 190
B) 200
C) 225
D) 230
E) none
Sol.   Relative speed = (120 + 80) km/hr [200 * 5/18] m/sec = [500/9] m/sec.   Let the length of the other tain be x metres.   Then, x + 270 / 9 = 500/9 ⇔ x + 270 = 500 ⇔ x = 230.   Answer 230
<result>D</result>
A 270 metres long train running at the speed of 120 kmph crosses another train running in opposite direction at the speed of 80 kmph in 9 seconds. What is the length of the other train?