How long will a boy take to run round a square field of side 60 meters, if he runs at the rate of 12km/hr? Choices:
A) 52 sec B) 45 sec C) 72 sec D) 25 sec E) 39 sec

Rationale: "speed = 12 km / hr = 12 * 5 / 18 = 10 / 3 m / sec distance = 60 * 4 = 240 m time taken = 240 * 3 / 10 = 72 sec answer is c"
Answer: C