PrepTest 141, Section 4, Question 10
Vacuum cleaner salesperson: To prove that this Super(54 more words not shown)
The vacuum cleaner salesperson's argument(8 more words not shown)
- Aignores the possibility(17 more words not shown)
- Btakes for granted(24 more words not shown)
- Ctakes for granted(16 more words not shown)
- Dignores the possibility(26 more words not shown)
- Eignores the possibility(24 more words not shown)
Reading the argument
Of course the second vacuum picked up dirt the first vacuum left behind. What other dirt was available?
That observation alone doesn't establish that the second machine is better. Imagine reversing the demonstration: use the Super XL first, then run the old vacuum over the carpet. If the old vacuum picks up additional dirt, the salesperson's reasoning would now call the old vacuum superior.
Maybe both machines need more than one pass. The original demonstration hasn't separated the benefit of another pass from the benefit of a better machine. Even collecting a tiny amount of additional dirt would satisfy the salesperson's description, without establishing superior performance.
What we’re looking for
For the flaw question, I'd look for that missing comparison. What would the Super XL leave behind if it went first? The argument needs more than the fact that a vacuum used second can collect something that remains.
Working the answers
- A
A better vacuum needn't collect every speck of dirt. The Super XL could leave some dirt and still outperform the old machine. A concerns perfect cleaning, while the conclusion concerns which of two machines is better.
- B
The salesperson isn't promising that the Super XL will remain superior when it reaches the old vacuum's age. The claim is about its present performance. How it will perform years later doesn't identify the problem with this demonstration.
- C
The conclusion says better than your old vacuum, not best among every vacuum available. C describes a different jump: showing superiority over one competitor and treating that as superiority over all competitors. Here, the problem is that even the comparison with the old machine hasn't been established.
- D
The old vacuum might have removed more dirt, but quantity alone wouldn't settle the comparison either. It might have picked up a large amount of easy-to-remove dirt, while the Super XL picked up a smaller amount that was much harder to extract. That is only a possibility, but it shows why the amount each collected doesn't by itself expose the decisive flaw. They faced different amounts and kinds of remaining dirt.
- ECorrect
If the Super XL would leave just as much dirt when used first, the demonstration hasn't shown an advantage for it. The apparent superiority could come from being used on a second pass. Reversing the order directly tests the assumption hidden in the salesperson's comparison; the mere presence of dirt in the second machine proves too little.
More Flaw questions
Learn the LSAT our way
Our platform drills Flaw questions at your level and adjusts as you improve.