A company's profit, \(\mathrm{P(n)}\), in dollars, from selling n items is modeled by the function \(\mathrm{P(n) = 17n - 459}\),...
GMAT Algebra : (Alg) Questions
A company's profit, \(\mathrm{P(n)}\), in dollars, from selling n items is modeled by the function \(\mathrm{P(n) = 17n - 459}\), where \(\mathrm{n \geq 0}\). The break-even point is the number of items the company must sell for the profit to be $0. What is the company's break-even point?
\(\mathrm{-27}\)
\(\mathrm{17}\)
\(\mathrm{27}\)
\(\mathrm{459}\)
1. TRANSLATE the problem information
- Given information:
- Profit function: \(\mathrm{P(n) = 17n - 459}\)
- Break-even point definition: number of items where profit = $0
- Need to find: the value of n when profit is zero
- This tells us we need to set \(\mathrm{P(n) = 0}\)
2. TRANSLATE the break-even condition
- Break-even means profit equals zero
- Mathematically: \(\mathrm{P(n) = 0}\)
- Substitute our function: \(\mathrm{17n - 459 = 0}\)
3. SIMPLIFY the equation to solve for n
- Starting equation: \(\mathrm{17n - 459 = 0}\)
- Add 459 to both sides: \(\mathrm{17n = 459}\)
- Divide both sides by 17: \(\mathrm{n = 459 ÷ 17}\)
- Calculate: \(\mathrm{n = 27}\)
Answer: C. 27
Why Students Usually Falter on This Problem
Most Common Error Path:
Weak TRANSLATE skill: Students may misunderstand what "break-even point" means and try to find when profit equals the number of items sold, or set up \(\mathrm{P(n) = n}\) instead of \(\mathrm{P(n) = 0}\).
This conceptual confusion leads them to solve equations like \(\mathrm{17n - 459 = n}\), getting \(\mathrm{n = 28.6}\), which doesn't match any answer choice. This leads to confusion and guessing.
Second Most Common Error:
Poor SIMPLIFY execution: Students correctly set up \(\mathrm{P(n) = 0}\) but make arithmetic errors when dividing \(\mathrm{459 ÷ 17}\), potentially calculating incorrectly and arriving at values that might lead them to select Choice (A) -27 or Choice (D) 459.
The Bottom Line:
This problem tests whether students can connect business terminology (break-even) with mathematical conditions (profit = 0). The algebra is straightforward once the correct equation is established.
\(\mathrm{-27}\)
\(\mathrm{17}\)
\(\mathrm{27}\)
\(\mathrm{459}\)