How long will a boy take to run round a square field of side 45 meters, if he runs at the rate of 9km/hr?	Answers:  A) 72 sec  B) 45 sec  C) 1 min  D) 32 sec  E) 25 sec

Rationale: "speed = 9 km / hr = 9 * 5 / 18 = 5 / 2 m / sec distance = 45 * 4 = 180 m time taken = 180 * 2 / 5 = 72 sec answer is a"
Answer: A