A total of 364 paper straws of equal length were used to construct two types of polygons: triangles and rectangles....
GMAT Algebra : (Alg) Questions
A total of 364 paper straws of equal length were used to construct two types of polygons: triangles and rectangles. The triangles and rectangles were constructed so that no two polygons had a common side. The equation \(3\mathrm{x} + 4\mathrm{y} = 364\) represents this situation, where x is the number of triangles constructed and y is the number of rectangles constructed. What is the best interpretation of \((\mathrm{x}, \mathrm{y}) = (24, 73)\) in this context?
If 24 triangles were constructed, then 73 rectangles were constructed.
If 24 triangles were constructed, then 73 paper straws were used.
If 73 triangles were constructed, then 24 rectangles were constructed.
If 73 triangles were constructed, then 24 paper straws were used.
1. TRANSLATE the ordered pair notation
- Given: \(\mathrm{(x, y) = (24, 73)}\)
- This means: \(\mathrm{x = 24}\) and \(\mathrm{y = 73}\)
2. TRANSLATE what the variables represent in context
- From the problem setup:
- \(\mathrm{x}\) = number of triangles constructed
- \(\mathrm{y}\) = number of rectangles constructed
- Therefore: \(\mathrm{x = 24}\) means 24 triangles, \(\mathrm{y = 73}\) means 73 rectangles
3. INFER the complete interpretation
- If \(\mathrm{(x, y) = (24, 73)}\), then we constructed:
- 24 triangles AND
- 73 rectangles
- This matches Choice A exactly
4. Verify the solution (optional)
- Check: \(\mathrm{3(24) + 4(73) = 72 + 292 = 364}\) ✓
Answer: A. If 24 triangles were constructed, then 73 rectangles were constructed.
Why Students Usually Falter on This Problem
Most Common Error Path:
Weak TRANSLATE skills: Students correctly identify that \(\mathrm{(x, y) = (24, 73)}\) means \(\mathrm{x = 24}\) and \(\mathrm{y = 73}\), but then mix up which variable represents which quantity. They might think x represents rectangles and y represents triangles, reversing the relationship.
This leads them to incorrectly conclude that 24 rectangles and 73 triangles were constructed, causing them to select Choice C (If 73 triangles were constructed, then 24 rectangles were constructed).
Second Most Common Error:
Poor TRANSLATE reasoning: Students misinterpret what \(\mathrm{y = 73}\) represents in the context. Instead of recognizing that y is the number of rectangles, they think y represents the number of paper straws used when 24 triangles are constructed.
This confusion about variable meaning leads them to select Choice B (If 24 triangles were constructed, then 73 paper straws were used).
The Bottom Line:
This problem tests whether students can accurately connect mathematical notation to real-world context. The key is carefully tracking what each variable represents throughout the interpretation process.
If 24 triangles were constructed, then 73 rectangles were constructed.
If 24 triangles were constructed, then 73 paper straws were used.
If 73 triangles were constructed, then 24 rectangles were constructed.
If 73 triangles were constructed, then 24 paper straws were used.