PT34.S3.Q21-- thirty years ago, the percentage of their income

DarklordDarklord Alum Member
edited May 2020 in Logical Reasoning 586 karma

Hi,

So I understand most of the reason why C is correct in this question, but how we can assume that if "single persons, on average, purchase the same kinds of food items" then this is consistent with all people who spent 2 times more money on food 30 years ago? After all, if something occurs on an average, doesn't that mean that it isn't necessarily true that all people do that something?

Hope my question makes sense
Any #help would be appreciated!

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  • jmarmaduke96jmarmaduke96 Member Sage ⭐
    2891 karma

    Hi there!

    You do indeed have the correct understanding of averages. However, keep in mind that we do not need the correct answer choice to say "all," so we do not need to assume that the average includes all.

    I think that there are two important points to make here. First of all, C is talking about the average for a person. So there might indeed people who purchase more than they used to, but these individuals are balanced out by individuals who purchase less than they used to. So I don't think that the fact that the answer choice doesn't say "all" is much of a knock against it.

    Furthermore, even if we needed C to say "all" to make the argument valid (and i'm not convinced that we do) this is not a sufficient assumption question. This is a psuedo-sufficient assumption question. While in general we are taught to think of PSA questions as being very close to SA questions with maybe an almost imperceptible assumption involved, I don't know if that is the most helpful format to attack these questions with. For the older tests I think that this framework works, but for the newer tests (the 80s in particular) the test writers have occasionally made the correct answers to PSA questions much weaker. There was one question I recall where the correct answer to a PSA question was much closer to a necessary assumption than a sufficient assumption.

    Due to this, I have found that for myself the most helpful way to think of PSA question is just to classify them as strengthening questions. The question stem for a PSA always says "most," so just keep that word in mind and do the question like a normal strengthening. If there are 4 totally irrelevant answers and one NA, then that is the correct answer. If there are several answers that would make the argument stronger but one that would make it valid, then you pick the one that would make it valid. On the newer tests this really has been important for me. I am evaluating each answer choice to find what gives the most possible support to the argument. It doesn't matter where that support falls on a 1-100 scale. As long as the answer choice that I select is higher on the scale than the other available choices, that is the one that I am going with. I hope this helps, let me know if I can clarify!

  • DarklordDarklord Alum Member
    586 karma

    Wow, I really like that insight on pseudo-sufficient assumption questions! This really helped-- thank you!

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