How long does a train 110 m long running at the speed of 72 km/hr takes to cross a bridge 140 m length?	Choose the correct choice from the following answers
A) 82.1 sec .  B) 12.5 sec  C) 19.1 sec .  D) 17.1 sec .  E) 42.1 sec .

Rationale: "speed = 72 * 5 / 18 = 20 m / sec total distance covered = 110 + 140 = 250 m . required time = 250 / 20 = 12.5 sec . answer : b"
Answer: B