In a model of automobile performance, Car A travels exactly 10 kilometers per liter of fuel, and Car B travels...
GMAT Two Part Analysis : (TPA) Questions
In a model of automobile performance, Car A travels exactly \(10\) kilometers per liter of fuel, and Car B travels exactly \(15\) kilometers per liter of fuel. According to this model. Car A requires exactly \(\mathrm{F}\) more liters of fuel than Car B to travel exactly \(\mathrm{N}\) kilometers.
In the table, select a value for F and a value for N that are jointly consistent with the information given. Make only two selections, one in each column.
Phase 1: Owning the Dataset
Visualization Selection
Since we're comparing two cars with different fuel efficiencies, let's use a comparison table:
Property | Car A | Car B |
Fuel Efficiency | 10 km/liter | 15 km/liter |
Fuel for N km | \(\mathrm{N/10}\) liters | \(\mathrm{N/15}\) liters |
Extra Fuel | F more liters | baseline |
Testing with Concrete Numbers
Let's test with N = 300 km to understand the relationship:
- Car A needs: \(\mathrm{300/10 = 30}\) liters
- Car B needs: \(\mathrm{300/15 = 20}\) liters
- Difference: \(\mathrm{30 - 20 = 10}\) liters
Phase 2: Understanding the Question
Breaking Down the Mathematical Relationship
The key statement tells us: "Car A requires exactly F more liters of fuel than Car B to travel exactly N kilometers."
This translates to:
- Fuel for Car A = \(\mathrm{N/10}\) liters
- Fuel for Car B = \(\mathrm{N/15}\) liters
- \(\mathrm{F = (N/10) - (N/15)}\)
Simplifying the Formula
Let's find a common denominator:
\(\mathrm{F = N/10 - N/15}\)
\(\mathrm{F = 3N/30 - 2N/30}\)
\(\mathrm{F = N/30}\)
Therefore: \(\mathrm{N = 30F}\)
Key Insight
We need to find values where one is exactly 30 times the other!
Phase 3: Finding the Answer
Systematic Check of F Values
Using our relationship \(\mathrm{N = 30F}\):
If \(\mathrm{F = 300}\) → N should be \(\mathrm{300 \times 30 = 9,000}\)
Is 9,000 in our choices? Yes! ✓
Stop here - we found our answer.
Verification
Let's verify with F = 300 and N = 9,000:
- Car A fuel for 9,000 km: \(\mathrm{9,000 ÷ 10 = 900}\) liters
- Car B fuel for 9,000 km: \(\mathrm{9,000 ÷ 15 = 600}\) liters (use calculator for precision)
- Difference: \(\mathrm{900 - 600 = 300}\) liters ✓
Phase 4: Solution
Our selections are:
- F = 300
- N = 9,000
These values satisfy the relationship where Car A needs exactly 300 more liters than Car B to travel exactly 9,000 kilometers.