Quote:
It is impossible to determine how far Noor has driven her car based solely on how many times she has had its oil changed, because she has not recorded how far she has driven her car since its last oil change. However, if she had not driven her car since its last oil change, one could calculate how far she has driven her car based solely on counting the number of oil changes and consulting her car’s manual, since Noor gets her car’s oil changed precisely as often as prescribed by the manual.
Which one of the following must be assumed in order for the argument’s conclusion to properly drawn?
A. The manual for Noor’s car prescribes getting the car’s oil changed once every 5,000 miles driven.
B. The manuals for different makes and models of car do not prescribe different distances between oil changes.
C. The manual for Noor’s car does not prescribe changing the oil more often after the car has been driven 100,000 miles than it does during the first 100,000 miles.
D. There is no way to figure out how far Noor has driven her car since its last oil change.
E. The manual for Noor’s car prescribes changing the car’s oil as frequently in warm weather as in cold weather.
Veritas Prpe Explanation
The correct answer is E.This is a necessary assumption question. The correct answer must be something that the argument cannot live without – a statement that, if it were false, would destroy the argument.
In this case, the conclusion is that “if she had not driven her car since its last oil change, one could calculate how far she has driven her car based solely on counting the number of oil changes and consulting her car’s manual.” But why? Presumably, because the manual calls for oil changes at regular distance intervals. However, the argument never actually establishes this information. We need to address it in an answer choice.
Answer E may seem irrelevant at first. However, the Assumption Negation Technique offers key insight. If E were not true – if “the manual for Noor’s car does not prescribe changing the car’s oil as frequently in warm weather as in cold weather” – then one would have to know the weather conditions in which Noor had driven her car in order to know the significance of the number of oil changes. Has Noor’s car had many oil changes? Maybe the car has been driven a long distance, or maybe it has been driven a shorter distance but in cold weather. Using only the manual and the number of oil changes, without other information about temperature, it would be quite impossible to determine the distance driven. So the absence of E destroys the conclusion. E is necessary, and therefore E is correct.
Answer A is tempting; if the manual prescribes an oil change every 5,000 miles, then one could definitely calculate Noor’s miles driven. But while A is sufficient, it is not necessary. Even if the manual didn’t prescribe an oil change every 5,000 miles, it might prescribe an oil change every 10,000 miles, or every 3,000 miles, or at some other regular distance interval. And in each of those cases it would be no less possible to count the oil changes and calculate the distance traveled. Because A is not necessary, it is incorrect.
Answer B is simply irrelevant. Whatever the manuals for other makes and models of cars may say, Noor’s car’s manual is the only one that matters – the argument explicitly describes consulting “her car’s manual.”
Answer C is another extremely tricky wrong answer. Certainly, if the manual prescribes a different interval between oil changes after 100,000 miles, it is more work to calculate the distance based on the number of oil changes. But why should it not still be possible, with a bit of math? If the manual prescribes, say, one oil change every 10,000 miles until 100,000 miles, and then one oil change every 5,000 miles thereafter, then a car with, for instance, 13 oil changes would have been driven 10(10)+3(5)=115,000 miles. Since it is still quite possible that one could calculate how far Noor has driven her car, C is not correct.
Answer D, though superficially appealing, is another irrelevant answer. The argument’s conclusion is conditional, specifically premised on “if she had not driven her car since its last oil change.” Any answer choice that attempts to address this issue is therefore pointless. Furthermore, even if there were a way to find out how far Noor had driven her car since her its last oil change, this would in no way render it impossible to calculate the distance she has driven her car – in fact, it would seemingly make it easier. So D is also a bit of a backwards wrong answer.
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31 Aug 2020, 20:00
72%
(02:23)
wrong 
