A rectangular plot measuring 90 metres by 40 metres is to be enclosed by wire fencing. If the poles of the fence are kept 5 metres apart, how many poles will be needed ?
Pick.
A) 55
B) 56
C) 57
D) 52
E) none of these

Rationale: "solution perimeter of the plot = 2 ( 90 + 40 ) = 260 m . ∴ number of poles = [ 260 / 5 ] = 52 m answer d"
Answer: D