Logical reasoning PrepTest 134 · Section 3 · Question 19

Incorrect. The argument is about the cost of the process, not the quality of the product, so this answer is out of scope.

Incorrect. The stimulus notes that the two processes cost about the same outside of waste disposal costs, so it doesn't matter how those costs are divided up between the individual line items. This answer is that trap we predicted!

Incorrect. This stimulus is talking about the current process and costs. It doesn't matter if those costs have been locked in for a while or just came down to be near parity.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen with Necessary Premise

Stimulus Summary:
Conventional tanning vs. Biological tanning
Differences - Substances (chemicals vs. catalysts); Biological creates about 20% less waste
Similarities - Substances cost about the same; Waste disposal is a substantial part of tanning costs
Therefore - Biological tanning is cheaper

Answer Anticipation:
When one type of logic dominates a stimulus—especially when it's a primary feature of the conclusion—you should frame your understanding of the stimulus around it. Here, the stimulus is very much a comparison between conventional tanning and biological tanning—especially with respect to their costs.

We learn that the substances used for both cost about the same, so that's not going to lead to a conclusion about one being cheaper. However, waste disposal is a significant cost of the process, and there's less biological waste than chemical waste from conventional tanning. That comparison features a difference related to cost, so it's the premise that the stimulus is relying on.

Which brings up a key assumption—that lower amount of waste means that it's cheaper to dispose of. Maybe the chemicals used in conventional tanning can be dumped down the drain, while the catalysts used in biological tanning need to be sent to a hazardous waste disposal site.

Note that, normally, we'd be considering other relevant costs to the process in drawing this comparison. However, the stimulus notes that the two processes "cost[] about the same" outside of waste disposal costs. Since this expected answer is invalidated by the argument, expect it to show up as a trap!

Answer Explanation:
This answer highlights the argument's jump between the amount of waste being disposed and the cost of disposing of that waste. If the biological catalyst waste does cost a lot more to dispose of than the chemicals, the argument falls apart.

Key Takeaway:
When a type of logic dominates a stimulus, or when it features prominently in the conclusion, frame your understanding of the argument around that—as we did with the comparative logic here.

Incorrect. The stimulus notes that the two processes cost about the same outside of waste disposal, so it doesn't require that any individual other part of the process is equivalent in cost between the two since they all wash out in the end. Another answer falling into the trap that we predicted!