How long will a boy take to run round a square field of side 40 meters, if he runs at the rate of 9km/hr? Choose the correct choice from the following choices:	A) 64 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 = 40 * 4 = 160 m time taken = 160 * 2 / 5 = 64 sec answer is a"
Answer: A