The quality of unrefined olive oil is not actually defined

[resolehtmai]

Another GMATPrep CR:
The quality of unrefined olive oil is not actually defined in terms of acidity, yet extensive tests have shown that the less free oleic acid an unrefined olive oil contains per liter, the higher its quality. The proportion of free oleic acid that an olive oil contains is an accurate measure of the oil’s acidity.
If the statements above are all true, which of the following conclusions is best supported by them?
A. When an olive oil is refined, the concentration of oleic acid in the oil is reduced.
B. The quality of an unrefined olive oil can be determined only by accurately measuring its acidity.
C. If an unrefined olive oil is intermediate in acidity between two other unrefined olive oils, it will also be intermediate between them in quality.
D. Free oleic acid is the only acid that unrefined olive oil contains.
E. People who judge the quality of unrefined olive oils actually judge those oils by their acidity, which the judges can taste.



OA: C

1) Can someone explain, Why is D wrong?
Stimulus says:-"The proportion of free oleic acid that an olive oil contains is an accurate measure of the oil’s acidity."
If proportion of free oleic acid = accurate measure of acidity, isn't it reasonable to assume that its the only acid that the olive oil contains?
D. Free oleic acid is the only acid that unrefined olive oil contains.

2) Also the stimulus says that "the less free oleic acid an unrefined olive oil contains per liter, the higher its quality."
This doesn't mean that its quality is only dependent on the quantity of oleic acid. There could be other impurities which could mitigate the contribution of less acidity.
As in C, it could be possible that the oil with intermediate acidity could contain very high amount of other impurities making it of least quality. Why do we assume that acidity is the only factor indicating quality?

[RonPurewal]

1) Can someone explain, Why is D wrong?
Stimulus says:-"The proportion of free oleic acid that an olive oil contains is an accurate measure of the oil’s acidity."
If proportion of free oleic acid = accurate measure of acidity, isn't it reasonable to assume that its the only acid that the olive oil contains?

No. There could be plenty of other acids.
They might be there in proportion to the oleic acid.
They might be so much weaker than oleic acid that their presence doesn't matter in the first place.
They might be other forms of oleic acid itself, other than the "free" one (whatever that means).

Also -- GMAC's "draw conclusion" questions will ALWAYS require you to combine two or more statements from the passage.
In other words, if you ever think that a conclusion can be drawn from only one statement in the passage, then ... something is going to be wrong with the conclusion. That's just not how they write the problems.

Here, you think you're deriving this conclusion from only one statement (the one you put in parentheses). That's a strong indicator that the choice is wrong.

By contrast, note that you have to combine the last 2 sentences to arrive at the correct conclusion.

[RonPurewal]

2) Also the stimulus says that "the less free oleic acid an unrefined olive oil contains per liter, the higher its quality."
This doesn't mean that its quality is only dependent on the quantity of oleic acid. There could be other impurities which could mitigate the contribution of less acidity.

You should read the statements literally. If the statement says "The less X, the more Y", then that means that ... the less X, the more Y.

What you're thinking here is "If all other factors are the same, then, the less X, the more Y". The problem is that the passage says no such thing.

[resolehtmai]

Also -- GMAC's "draw conclusion" questions will ALWAYS require you to combine two or more statements from the passage.
In other words, if you ever think that a conclusion can be drawn from only one statement in the passage, then ... something is going to be wrong with the conclusion. That's just not how they write the problems.

This one is a great takeaway for me. thanks a lot.

[RonPurewal]

This one is a great takeaway for me. thanks a lot.

You're welcome. It should be blazingly clear if you just look at a few problems of that type, but, sure.

Note also that there's a contrast here with RC inference/detail questions, which normally don't make you combine statements. Sometimes they do, but more often you just find one statement in the passage and "flip" it. (E.g., you might take This method is especially useful because it applies to all kinds of metals, and "infer" that This method would be less useful if it applied to fewer kinds of metals.)

The reason for the difference is that finding things is a primary challenge in RC, but not in CR, where the passages are only a few lines long. If it's hard enough to find things, you won't also have to combine them.

[750plus]

The quality of unrefined olive oil is not actually defined in terms of acidity, yet extensive tests have shown that the less free oleic acid an unrefined olive oil contains per liter, the higher its quality. The proportion of free oleic acid that an olive oil contains is an accurate measure of the oil’s acidity.

I just feel that the first statement is contradicted by what follows in the passage? First, it says that the quality of oil can't be governed in terms of acidity. And then it goes on to say that proportion of oleic acid in oil determines the acidity, and less free oleic acid means higher the quality. So, basically the acidity present in the olive oil determines its quality?

Isn't this contradicting the written statements itself?

[RonPurewal]

the first statement is about how something is defined by scientists—like, literally, "what would be the definition in a textbook?"

__

analogously... "temperature" is scientifically defined by something having to do with the triple point of water.
higher temperatures "feel hotter" to human beings, but, temperature is not DEFINED in any way having to do with the human perception of "hot".