The length of each edge of a box is 29 inches. Each side of the box is in the shape...
GMAT Geometry & Trigonometry : (Geo_Trig) Questions
The length of each edge of a box is \(29\) inches. Each side of the box is in the shape of a square. The box does not have a lid. What is the exterior surface area, in square inches, of this box without a lid?
1. TRANSLATE the problem information
- Given information:
- Edge length: 29 inches
- Each side is square-shaped
- Box has no lid
- Need exterior surface area
- What this tells us: We have a cube-shaped container missing its top face
2. INFER how many faces to count
- A complete cube has 6 square faces
- Since there's no lid, we have: 1 bottom + 4 sides = 5 faces total
- All faces are congruent squares with 29-inch sides
3. Calculate area of one square face
- Area of square = \(\mathrm{side}^2\)
- Area = \(29^2 = 841\) square inches
4. INFER the total surface area approach
- Surface area = sum of all face areas
- Since all 5 faces are identical: Total = \(5 \times \mathrm{(area\ of\ one\ face)}\)
- Total surface area = \(5 \times 841 = 4,205\) square inches
Answer: 4205
Why Students Usually Falter on This Problem
Most Common Error Path:
Weak TRANSLATE skill: Students misinterpret 'box without a lid' and count 6 faces instead of 5
Many students automatically think 'cube = 6 faces' without carefully reading that the box has no lid. They calculate \(6 \times 841 = 5,046\), leading to an incorrect answer that's too large.
Second Most Common Error:
Inadequate SIMPLIFY execution: Students make arithmetic errors when calculating \(29^2\) or the final multiplication
Some students might miscalculate \(29^2\) (perhaps getting 829 instead of 841) or make errors in \(5 \times 841\), leading to various incorrect values.
The Bottom Line:
This problem tests careful reading comprehension combined with 3D spatial reasoning. Students must visualize that removing the lid from a cube leaves exactly 5 faces, then execute straightforward area calculations accurately.