At a wildlife sanctuary, two methods are usually employed to tranquili

Question

At a wildlife sanctuary, two methods are usually employed to tranquilize injured animals for treatment: injections and sprays. Although tranquilizer sprays are delivered faster, the overall time taken by the injection to tranquilize an animal is less than that taken by the spray. Therefore, using injections is a more effective method than using the tranquilizer spray.

Which of the following is an assumption on which the argument depends?

A. The effects of tranquilizer injections last much longer than the effects of tranquilizer sprays.

B. The effectiveness of a method is inversely proportional to the time it takes to tranquilize an animal.

C. Using the tranquilizer spray is not a less effective method than administering tranquilizer injections in the case of sedating large animals for vaccination.

D. Tranquilizers cannot be delivered faster than currently possible with the use of better technologies.

E. The effect of tranquilizer injections occurs faster than that of tranquilizer sprays because the injections are administered intravenously.

IanStewart · Answer

It's not clear what the vague word "effective" means in the conclusion, and since sprays have some advantages and injections have some advantages, the assumption behind the argument is that the advantages of injections (injections take less time to tranquilize and animal) are an important part of what makes a method "more effective".

But no answer choice says that. Not one of the answers is an  assumption  here. Most of the answers are clearly wrong -- C is not about treating injured animals, the only animals the stem discusses, so is irrelevant; D has nothing to do with the comparison between sprays and injections so is irrelevant; we don't care by what mechanism injections are effective, only that they are effective, so E is irrelevant.

It's impossible to evaluate A, because there's no way to know what "more effective" means. If "more effective" means "remains tranquilized longer", then A is certainly an assumption (but then we didn't need to read any of the evidence in the stem). If "more effective" means something else, though, then A is not an assumption.

B, which is listed as the OA, is clearly not an assumption. If you insert B in the argument, that clearly makes the argument valid -- if we know that effectiveness and tranquilization time are inversely proportional, then the method that takes the least time is automatically, by definition, the most effective. But that's not what an assumption is. An assumption is something that must be true for the argument to hold. We don't need to assume that there exists a  specific type of proportionality  between effectiveness and tranquilization time for this argument to be valid.

So there is no good answer to this question.

J2S2019 · Answer

negated statement of B
"The effectiveness of a method is inversely proportional to the time it takes to tranquilize an animal."

Negated - "The effectiveness of a method is  Directly  proportional to the time it takes to tranquilize an animal."

This shatters the conclusion the most, hence the correct answer

IanStewart · Answer

I would not be surprised if the OE uses a negation test in this way to justify the OA. But that's not the correct negation of answer B. The correct negation would be "the effectiveness is not inversely proportional to the time it takes to tranquilize". Just because two things are not inversely proportional does not make them directly proportional. There might be no relationship whatsoever between the two things, for example. The distance between Earth and Halley's comet is not inversely proportional to shoe sales, for example, but that doesn't make them directly proportional. They're simply unrelated (as far as I know!).

That's one reason I prefer to avoid techniques like "negation tests" altogether; it's a test that's easy to misuse, and it's usually easier to answer questions directly rather than reversing them and trying to think about them backwards.

At a wildlife sanctuary, two methods are usually employed to tranquili

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