A right pyramid has a square base. The side length of the square base is 13/3 meters, and the height...
GMAT Geometry & Trigonometry : (Geo_Trig) Questions
A right pyramid has a square base. The side length of the square base is \(\frac{13}{3}\) meters, and the height of the pyramid is \(\frac{7}{2}\) meters. What is the volume, in cubic meters, of the pyramid?
\(\frac{1183}{36}\)
\(\frac{1183}{54}\)
\(\frac{1183}{27}\)
\(\frac{1183}{18}\)
1. TRANSLATE the problem information
- Given information:
- Right pyramid with square base
- Side length of square base: \(\frac{13}{3}\) meters
- Height of pyramid: \(\frac{7}{2}\) meters
- Need to find: Volume in cubic meters
- What this tells us: We have all the measurements needed to apply the pyramid volume formula.
2. INFER the approach
- Since we have a pyramid, we'll use: \(\mathrm{V} = \frac{1}{3} \times \mathrm{Base\:Area} \times \mathrm{Height}\)
- First we need the base area, then substitute everything into the volume formula
- The base is square, so we'll need to square the side length
3. Calculate the base area
- Base Area = \(\left(\mathrm{side\:length}\right)^2 = \left(\frac{13}{3}\right)^2\)
- Base Area = \(\frac{169}{9}\) square meters
4. SIMPLIFY by applying the volume formula
- \(\mathrm{V} = \frac{1}{3} \times \frac{169}{9} \times \frac{7}{2}\)
- Multiply the numerators: \(1 \times 169 \times 7 = 1183\)
- Multiply the denominators: \(3 \times 9 \times 2 = 54\)
- \(\mathrm{V} = \frac{1183}{54}\) cubic meters
Answer: B. \(\frac{1183}{54}\)
Why Students Usually Falter on This Problem
Most Common Error Path:
Weak SIMPLIFY execution: Students make arithmetic errors when multiplying the fractions, particularly when calculating \(1 \times 169 \times 7 = 1183\) or \(3 \times 9 \times 2 = 54\). Common mistakes include getting 1173 instead of 1183 in the numerator, or miscalculating the denominator as 36 or 27.
This may lead them to select Choice A (\(\frac{1183}{36}\)) or Choice C (\(\frac{1183}{27}\)).
Second Most Common Error:
Missing conceptual knowledge about pyramid volume: Students might confuse the pyramid volume formula with other volume formulas, forgetting the \(\frac{1}{3}\) factor and just multiplying Base Area × Height directly.
This leads to getting \(\frac{1183}{18}\) and selecting Choice D.
The Bottom Line:
This problem tests careful fraction arithmetic more than complex geometric reasoning. The key is systematically working through the multiplication without rushing the calculations.
\(\frac{1183}{36}\)
\(\frac{1183}{54}\)
\(\frac{1183}{27}\)
\(\frac{1183}{18}\)