A train 400 m long can cross an electric pole in 10 sec and then find the speed of the train?  Choose the correct choice from the following choices:  A) 165 kmph  B) 144 kmph  C) 172 kmph  D) 175 kmph  E) 178 kmph

Rationale: "length = speed * time speed = l / t s = 400 / 10 s = 40 m / sec speed = 40 * 18 / 5 ( to convert m / sec in to kmph multiply by 18 / 5 ) speed = 144 kmph answer : b"
Answer: B