PrepTest 126, Section 1, Question 4
Among the various models of Delta vacuum cleaners,(38 more words not shown)
The argument's conclusion is properly(9 more words not shown)
- AFor each Delta(18 more words not shown)
- BOne can accurately(19 more words not shown)
- CAll Delta vacuum(9 more words not shown)
- DFor any two(19 more words not shown)
- EOne cannot accurately(17 more words not shown)
Reading the argument
A powerful motor might help. Why think it tells us everything?
A vacuum's attachments could matter too. Perhaps one covers a wide strip of carpet while another requires many more passes. Those are possibilities to consider, not facts the argument gives us. They help explain why I can accept that the motor matters without assuming it's the only thing that matters.
The author points to a different feature: dust filtration. Even vacuums with equally powerful motors can have very different filtration systems. But does that difference affect how well they clean? If it were merely an aesthetic difference, it wouldn't establish anything about cleaning performance.
At first, these might seem like two facts about vacuums. But the question asks us to make a conclusion follow, so we need to see how the statements fit together. Which one supports the other? The filtration differences explain why motor power alone might not predict performance. Saying the motor is a poor predictor doesn't explain why the filters differ. That makes the first sentence the conclusion.
What we’re looking for
Now we can supply the missing connection: differences in filtration need to make a real difference to cleaning. Otherwise, the second sentence gives us no reason to accept the first.
Working the answers
- ACorrect
Filtration has a significant effect on cleaning performance. Now two vacuums can have the same motor power yet differ in another feature that materially affects how well they clean. Knowing only the motor power leaves out that important difference, which supports the author's conclusion.
- B
This connects filtration with motor power. We need to connect filtration with cleaning effectiveness. Being able to infer the motor's power from the filtration system still doesn't tell us whether differences in filtration make the vacuum clean better or worse.
- C
Read the direction carefully. C starts with vacuums that clean equally well and says they have equal motor power. Our problem starts with equal motor power and asks whether that guarantees equal cleaning performance. C doesn't answer that question. It could be true while equally powerful motors accompanied different cleaning results.
- D
This holds filtration constant and compares motor power. It could show that motor power matters when that other feature stays the same. But we already allow the motor to matter. We need to show that differences in filtration matter too, so that the motor alone cannot settle the comparison. D never supplies that link.
- E
Motor power could be information we need without being all the information we need. For example, we might need both motor power and filtration to judge a vacuum. E doesn't say whether filtration contributes anything, so it doesn't finish the author's argument.
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