Final answer:
Adding the number of stones per side to get the total is incorrect if the stones are unevenly distributed, some are missing, or if the shape is different than expected. Calculations must account for these factors to avoid an erroneous total.
Step-by-step explanation:
When calculating the total number of stones around a shape, simply adding the number of stones per side can lead to an incorrect total if some assumptions are not met. Option a, b, and c all provide scenarios where simply adding the numbers would be erroneous:
- a. The stones are not evenly distributed: If stones are spaced irregularly along the sides, the count per side might not reflect the actual total.
- b. Some stones are missing from the count: If there are gaps or stones have been omitted from counting, the result will be less than the true total.
- c. The prototype has a different shape: If the actual shape differs from the prototype or expected shape, the number of stones required for the perimeter would change.
Option d, "Stones are not used in calculating perimeters," is incorrect because in context, stones can represent units of length, thus are used to calculate the perimeter in a practical sense. The error in the total arises from discrepancies in distribution, quantity, or shape compared to what the calculation assumed. Always ensure accurate measurements and observations when tallying such numbers.