PrepTest 144, Section 3, Question 21
Consumer magazine: Because front-loading washers use less water(39 more words not shown)
Which one of the following(11 more words not shown)
- AAll top-loading washing(7 more words not shown)
- BA laundry detergent(16 more words not shown)
- CA washing machine(14 more words not shown)
- DA laundry detergent(15 more words not shown)
- EWashers that use(10 more words not shown)
Reading the argument
Why do we have to buy the special detergent? What about an ordinary liquid detergent or a pod?
Those are possibilities to check, not facts about which products work in a real washer. The argument gives us a problem with ordinary powder: it doesn't dissolve readily in the lower amount of water used by a front-loading machine. Then it says a specially formulated detergent is required to get the clothes really clean.
My first concern is that the magazine has skipped other possible options. Ruling out one type of detergent doesn't automatically leave only the special kind. A nonspecial detergent that worked would undermine that claim of necessity.
What we’re looking for
We're asked for an assumption the argument requires. Keep that concern in mind, but check the whole path from the powder's failure to dissolve to the claim about getting clothes clean.
Working the answers
- A
Top-loading machines don't have to use identical amounts of water. One could use more than another while both use more than the front-loading machines being discussed. Exact equality between top loaders is unnecessary to the argument about which detergent a front loader needs.
- B
The special detergent could dissolve equally well in both types of machine. It could even dissolve more readily in a top loader while still working well enough in a front loader. The argument needs a claim about cleaning in the front-loading machine, not a claim that this detergent dissolves better there than elsewhere.
- C
This gives us a much broader rule: every washing machine needs a detergent specially formulated for it. Such a rule would support the conclusion about front loaders, but the argument doesn't need it to cover every machine. Top loaders could work perfectly well with ordinary detergent while the magazine's claim about front loaders remained intact.
- DCorrect
Here's an earlier link we also need: dissolving readily must matter to getting the clothes really clean. If ordinary powder could clean the clothes completely despite dissolving poorly, the stated reason for rejecting it would fail.
D ties the evidence about dissolving to the conclusion about cleaning. It doesn't settle our initial concern about other detergents, but it doesn't have to settle every concern to be required. The distinction is between an assumption the reasoning needs and an assumption that would establish the entire conclusion by itself.
- E
We don't need to rank the cleaning performance of machines by how much water they use. A front loader using the right detergent could clean just as well as a top loader. The magazine's argument concerns the detergent needed in one kind of machine, not which machines ultimately produce cleaner clothes.
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