In what time will a railway train 40 m long moving at the rate of 36 kmph pass a telegraph post on its way?  Choose the correct choice from the following answers
A) 3 sec B) 4 sec C) 5 sec D) 6 sec E) 7 sec

Rationale: "t = 40 / 36 * 18 / 5 = 4 sec answer : b"
Answer: B