A wind turbine completes 900 revolutions in 50 minutes. At this rate, how many revolutions per minute does this turbine...
GMAT Problem-Solving and Data Analysis : (PS_DA) Questions
A wind turbine completes \(900\) revolutions in \(50\) minutes. At this rate, how many revolutions per minute does this turbine complete?
1. TRANSLATE the problem information
- Given information:
- 900 revolutions completed
- 50 minutes elapsed
- Find: revolutions per minute (rate)
2. INFER the mathematical approach
- "Revolutions per minute" means "how many revolutions in each minute"
- To find rate, divide total quantity by total time
- Set up: \(\mathrm{900\,\text{revolutions} ÷ 50\,\text{minutes}}\)
3. SIMPLIFY the calculation
- \(\mathrm{900 ÷ 50 = 18}\)
- Check: \(\mathrm{18 × 50 = 900}\) ✓
Answer: A. 18
Why Students Usually Falter on This Problem
Most Common Error Path:
Weak TRANSLATE skill: Students misunderstand what "per minute" means and perform the wrong operation instead of division.
Some students might add the numbers \(\mathrm{(900 + 50 = 950)}\) or subtract them \(\mathrm{(900 - 50 = 850)}\) because they don't recognize that "per" indicates division. This may lead them to select Choice B (850) or Choice C (950).
The Bottom Line:
The key insight is recognizing that "per minute" is asking for a rate, which always requires division of the total quantity by the total time. Once students understand this relationship, the problem becomes a straightforward division calculation.