A car dealership has a total of 80 vehicles on its lot. Of these vehicles, 30 are cars and the...
GMAT Problem-Solving and Data Analysis : (PS_DA) Questions
A car dealership has a total of 80 vehicles on its lot. Of these vehicles, 30 are cars and the rest are trucks. If \(10\%\) of the trucks on the lot are white, how many white trucks are on the lot?
- 3
- 5
- 8
- 50
1. TRANSLATE the problem information
- Given information:
- Total vehicles on lot: 80
- Cars: 30
- The rest are trucks
- 10% of trucks are white
- What this tells us: We need to find trucks first, then calculate 10% of that amount
2. INFER the approach
- This is a two-step problem
- Step 1: Find how many trucks there are
- Step 2: Calculate 10% of that truck total
3. SIMPLIFY to find the number of trucks
- \(\mathrm{Total\ vehicles = Cars + Trucks}\)
- \(\mathrm{80 = 30 + Trucks}\)
- \(\mathrm{Trucks = 80 - 30 = 50}\)
4. SIMPLIFY to find 10% of the trucks
- \(\mathrm{White\ trucks = 10\%\ of\ 50}\)
- \(\mathrm{White\ trucks = 0.10 \times 50 = 5}\)
Answer: B) 5
Why Students Usually Falter on This Problem
Most Common Error Path:
Weak TRANSLATE skill: Students misinterpret "10% of the trucks" and instead calculate 10% of all 80 vehicles.
They think: "\(\mathrm{10\%\ of\ 80 = 8\ white\ trucks}\)"
This leads them to select Choice C (8).
Second Most Common Error:
Poor INFER reasoning: Students recognize they need to find trucks first but get confused about the relationship between cars and trucks.
They might think trucks = 80 + 30 = 110, or get lost in the multi-step nature of the problem.
This causes them to get stuck and guess among the remaining choices.
The Bottom Line:
This problem tests whether students can break down word problems into logical steps and resist the temptation to use the most obvious numbers (like taking 10% of 80 directly).