How long will a boy take to run round a square field of side 20 meters, if he runs at the rate of 12km/hr? Pick: A) 52 sec B) 45 sec C) 60 sec D) 24 sec E) 39 sec

Rationale: "speed = 12 km / hr = 12 * 5 / 18 = 10 / 3 m / sec distance = 20 * 4 = 80 m time taken = 80 * 3 / 10 = 24 sec answer is d"
Answer: D