The table summarizes the number of objects in each group.GroupNumber of objectsA375B54C690D81Total1,200The number of objects in group C is p%...
GMAT Problem-Solving and Data Analysis : (PS_DA) Questions
The table summarizes the number of objects in each group.
| Group | Number of objects |
|---|---|
| A | 375 |
| B | 54 |
| C | 690 |
| D | 81 |
| Total | 1,200 |
The number of objects in group C is \(\mathrm{p}\%\) of the number of objects in group A. What is the value of p?
1. TRANSLATE the problem information
- Given information:
- Group A has 375 objects
- Group C has 690 objects
- Group C is \(\mathrm{p\%}\) of Group A
- What this tells us: We need to find what percentage 690 is of 375
2. TRANSLATE the percentage relationship into an equation
- The phrase "690 is p% of 375" becomes: \(\mathrm{690 = \frac{p}{100} \times 375}\)
- This is the fundamental percentage equation: \(\mathrm{Part = \frac{Percent}{100} \times Whole}\)
3. SIMPLIFY the equation to solve for p
- First, multiply out the right side:
\(\mathrm{690 = \frac{p}{100} \times 375 = 3.75p}\) - Now divide both sides by 3.75:
\(\mathrm{p = 690 \div 3.75}\) - Calculate the division (use calculator):
\(\mathrm{p = 184}\)
Answer: 184
Why Students Usually Falter on This Problem
Most Common Error Path:
Weak TRANSLATE skill: Students confuse which number should be the "whole" and which should be the "part"
They might incorrectly think: "375 is p% of 690" and set up \(\mathrm{375 = \frac{p}{100} \times 690}\), leading to \(\mathrm{p = 375 \div 6.9 \approx 54.3}\). This leads to confusion since 54.3 isn't a clean answer, causing them to abandon systematic solution and guess.
Second Most Common Error:
Poor SIMPLIFY execution: Students make calculation errors when computing \(\mathrm{690 \div 3.75}\)
They might approximate incorrectly (like \(\mathrm{690 \div 4 = 172.5}\)) or make division mistakes, leading to answers that don't match the expected result. This causes them to second-guess their setup and potentially guess randomly.
The Bottom Line:
This problem tests whether students can correctly translate a percentage statement into mathematical form and then execute the arithmetic accurately. The key insight is recognizing that "C is p% of A" means \(\mathrm{C = \frac{p}{100} \times A}\), not the reverse.