In a long-distance road test, two cars of different makes were driven on the same 600-mile route. One of the...
GMAT Critical Reasoning : (CR) Questions
In a long-distance road test, two cars of different makes were driven on the same 600-mile route. One of the cars, a gasoline (petrol) powered car, used more fuel on the route than did the other, a diesel powered car. Clearly, the diesel engine is more fuel-efficient than the gasoline engine.
Which of the following would, if true, most strengthen the argument?
Passage Analysis:
Text from Passage Analysis In a long-distance road test, two cars of different makes were driven on the same 600-mile route.
- What it says: Sets up a controlled test with two different cars on identical 600-mile routes
- What it does: Establishes the testing scenario and ensures fair comparison conditions
- What it is: Study setup/experimental design
- Visualization: Car A and Car B both drive the same 600-mile route
One of the cars, a gasoline (petrol) powered car, used more fuel on the route than did the other, a diesel powered car.
- What it says: The gas car burned more fuel than the diesel car on this test
- What it does: Provides the key experimental result that builds on the test setup
- What it is: Study finding
- Visualization: Gas car uses 25 gallons, Diesel car uses 18 gallons (same 600 miles)
Clearly, the diesel engine is more fuel-efficient than the gasoline engine.
- What it says: Concludes that diesel engines are generally more fuel-efficient than gas engines
- What it does: Makes a broad generalization based on the single test result from the previous statements
- What it is: Author's conclusion
Argument Flow:
The argument starts with a controlled test setup, presents the fuel consumption results, then jumps to a broad conclusion about engine efficiency in general.
Main Conclusion:
Diesel engines are more fuel-efficient than gasoline engines.
Logical Structure:
The author uses one specific test result (diesel car used less fuel than gas car on same route) as evidence to support a general claim about diesel vs. gasoline engine efficiency. This is a classic case of drawing a broad conclusion from limited evidence.
Prethinking:
Question type:
Strengthen - We need to find information that would make us more confident that diesel engines are generally more fuel-efficient than gasoline engines based on this single test.
Precision of Claims
The conclusion makes a broad generalization about engine types (diesel vs gasoline) based on quality comparison (fuel efficiency) from a single test between two specific cars.
Strategy
To strengthen this argument, we need to address potential weaknesses in drawing a broad conclusion from one test. The main gaps are:
- this was just one test with two specific cars - maybe other factors affected the results
- the cars were different makes so maybe the difference wasn't about the engine type
- we don't know if the test conditions were truly fair for comparing engine efficiency
This tells us the diesel car is popular for fuel economy, but this doesn't strengthen our conclusion. We need evidence about actual performance, not just reputation or popularity. This is circular reasoning - we're trying to prove diesel is more efficient, so pointing to its reputation for efficiency doesn't add new evidence.
This information about what's typical for this car make is irrelevant to our conclusion. Whether most cars of this make have gas or diesel engines doesn't tell us anything about the relative efficiency of the two engine types in our test.
This significantly strengthens the argument! If the diesel car used less fuel despite facing greater wind resistance (which would typically increase fuel consumption), this makes the case for diesel efficiency much stronger. It shows that diesel performed better even under worse conditions, making our conclusion more reliable.
This general statement about how fuel economy varies with speed doesn't help our specific comparison. It doesn't tell us anything about the relative performance of diesel vs. gasoline engines in our test.
This would actually weaken the argument. If the gasoline car faced greater wind resistance and still used more fuel, we might wonder if the diesel car only performed better because it had easier driving conditions, not because of superior engine efficiency.