The minimum value of x is 12 less than 6 times another number n. Which inequality shows the possible values...
GMAT Algebra : (Alg) Questions
The minimum value of \(\mathrm{x}\) is 12 less than 6 times another number \(\mathrm{n}\). Which inequality shows the possible values of \(\mathrm{x}\)?
\(\mathrm{x \leq 6n - 12}\)
\(\mathrm{x \geq 6n - 12}\)
\(\mathrm{x \leq 12 - 6n}\)
\(\mathrm{x \geq 12 - 6n}\)
1. TRANSLATE the problem information
- Given information:
- The minimum value of \(\mathrm{x}\) is 12 less than 6 times another number \(\mathrm{n}\)
- What this tells us:
- We need to express "6 times n" as \(\mathrm{6n}\)
- We need to express "12 less than 6n" as \(\mathrm{6n - 12}\)
- This value \(\mathrm{(6n - 12)}\) represents the smallest possible value for \(\mathrm{x}\)
2. INFER what minimum value means for inequalities
- Key insight: If \(\mathrm{6n - 12}\) is the minimum value of \(\mathrm{x}\), then:
- \(\mathrm{x}\) can equal \(\mathrm{6n - 12}\) (\(\mathrm{x}\) reaches its minimum)
- \(\mathrm{x}\) can be greater than \(\mathrm{6n - 12}\) (\(\mathrm{x}\) exceeds its minimum)
- \(\mathrm{x}\) cannot be less than \(\mathrm{6n - 12}\) (this would violate the minimum)
- Therefore: \(\mathrm{x \geq 6n - 12}\)
3. Match with answer choices
Looking at the options, choice B shows \(\mathrm{x \geq 6n - 12}\), which matches our reasoning.
Answer: B
Why Students Usually Falter on This Problem
Most Common Error Path:
Weak TRANSLATE skill: Students incorrectly translate "12 less than 6n" as "\(\mathrm{12 - 6n}\)" instead of "\(\mathrm{6n - 12}\)"
The phrase "12 less than [something]" means "[something] - 12", not "12 - [something]". This translation error leads students to think the minimum value is \(\mathrm{12 - 6n}\).
This may lead them to select Choice D (\(\mathrm{x \geq 12 - 6n}\)).
Second Most Common Error:
Poor INFER reasoning: Students correctly translate to get \(\mathrm{6n - 12}\) but misunderstand what "minimum value" means for inequalities
They might think: "If \(\mathrm{6n - 12}\) is the minimum, then \(\mathrm{x}\) must be less than or equal to this value" – confusing minimum with maximum.
This may lead them to select Choice A (\(\mathrm{x \leq 6n - 12}\)).
The Bottom Line:
This problem tests two critical skills working together: precise language translation and understanding the logical relationship between minimum values and inequality directions. Success requires both accurate translation and conceptual clarity about what "minimum" means in mathematical contexts.
\(\mathrm{x \leq 6n - 12}\)
\(\mathrm{x \geq 6n - 12}\)
\(\mathrm{x \leq 12 - 6n}\)
\(\mathrm{x \geq 12 - 6n}\)