How long will a boy take to run round a square field of side 50 meters, if he runs at the rate of 9km/hr?	Pick one.
A) 80 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 = 50 * 4 = 200 m time taken = 200 * 2 / 5 = 80 sec answer is a"
Answer: A