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PrepTest 73, Logical Reasoning 2, Question 1


Question one, when a question asks you to undermine the argument, then that's a weakened question. And on a weakened question, your job is to attack the arguments assumptions. But of course, in order to know the arguments assumptions, you have to understand the argument, which means knowing its conclusion and its evidence. So here the conclusion come to the very end of the stimulus.

Clearly, the key word says, clearly, then chocolate interferes with one's ability to taste coffee. The evidence for this is a study. The first sentence just tells us there was a study and there were ten people in it, who were asked to take samples of coffee and rank them. Half of the people in the group were given chocolate with their coffee, and they found that the coffee all tasted pretty much the same.

Five other people didn't get chocolate, and they were able to detect differences. So since the people who couldn't taste the coffee had just eaten chocolate, that's why the argument says that chocolate interferes with one's ability to taste coffee. Now to weaken the argument, we have to attack its assumptions. The things that the author never said that has to be true in order for the evidence given to be able to prove the conclusion.

Since this argument is based pretty much entirely on a study, it has the assumptions that go with any study. The first is that the sample in this study was big enough. They asked enough people. The second is, that there wasn't any bias in the way that the sample was made. And the third is, that the people in the study were representative.

Meaning, there was nothing special about them that would throw off the results. Nothing special about the way they taste, about what they think about coffee, anything we can change the way we view the study, and whether it's relevant to this conclusion. So the correct answer is gonna attack on those assumptions, let's see what we've got to work with.

Answer choice A, well, this would actually strengthen the argument. If the ten people were randomly assigned to either group, that helps us believe that there wasn't a source of bias in the study. So as we're trying to weaken the argument, this is not our answer. Answer choice B, would also strengthen the argument. If they got the same result with the experiment done to a larger number of people, it suggests that, yeah, there were enough people in the original experiment it wasn't too small.

So answer choice B also not our answer. Answer choice C., chocolate is normally consumed as a solid whereas coffee is normally consumed as a liquid. This is an irrelevant comparison. How chocolate is normally eaten doesn't really matter. What matters is if the way they ate it in the study would change the effects in any way, and this doesn't tell us that it would.

So answer choice D, the five people who were originally given chocolate were asked a week later to taste coffee samples without chocolate, and they still detected no differences between the coffee samples. Now this answer is going to be our answer because it's attacking that representativeness assumption. Apparently when they grabbed five people through the study they seemed to have just happened to have grabbed five people who don't know the difference between coffees or can't taste the difference between coffees.

I suggest that it wasn't the chocolate, it's just something special about these people, since when you take the chocolate away, they still don't detect any differences. So answer choice D works, what's wrong with E? So answer choice E gives us some distinctions between the group that were able to taste the coffee.

Some of them got subtle differences. Some of them thought that they were big differences. What matters is they thought they were differences, the exact nature and extent of the differences doesn't really matter. So, and this answer doesn't work. The answer is D.

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