In what time will a railway train 30 m long moving at the rate of 36 kmph pass a telegraph post on its way?  Pick:
A) 5 sec
B) 4 sec
C) 3 sec
D) 6 sec
E) 1 sec

Rationale: "t = 30 / 36 * 18 / 5 = 3 sec answer : c"
Answer: C