A rectangular plot measuring 90 meters by 50 meters is to be enclosed by wire fencing. If the poles of the fence are kept 5 meters apart. How many poles will be needed?
Pick one:
A) 34 B) 77 C) 36 D) 56 E) 91

Rationale: "explanation : perimeter of the plot = 2 ( 90 + 50 ) = 280 m no of poles = 280 / 5 = 56 m answer : d"
Answer: D