Fencing poles: A rectangular plot 90 m by 50 m is to be enclosed with poles placed every 5 m along the boundary. How many poles are needed in total?

Introduction / Context:
Regular spacing of poles along a closed perimeter uses division of the total perimeter by spacing (when perimeter is an exact multiple).

Given Data / Assumptions:

• Dimensions: 90 m by 50 m
• Spacing: 5 m
• Perimeter is a multiple of spacing (no partial gap at the end).

Concept / Approach:
Total number of poles = Perimeter / Spacing, when the start and end coincide on a closed loop and perimeter is exactly divisible by spacing.

Step-by-Step Solution:

Verification / Alternative check:
Each 5 m segment corresponds to one spacing; with 280 m, this yields exactly 56 segments/poles, no remainder.

Why Other Options Are Wrong:
45, 55, 60, 65 reflect miscounting corners or not using total perimeter correctly.

Common Pitfalls:
Adding an extra pole for the starting point even when the spacing closes exactly, or miscomputing perimeter.

Final Answer:
56