Auditor: XYZ, a construction company, purchased 20 new trucks 3 years ago, and there is no record of any of those trucks being sold last year. Records indicate, however, that XYZ sold off all of its diesel-powered trucks last year. We can thus conclude that none of the 20 trucks purchased 3 years ago were diesel powered.
No record of those trucks were sold last year —> none of them were diesel powered.
(Those sold last year = diesel)
Leap: Just because they were not sold last year does NOT indicate that non of them were not sold at any time before that. So it is possible that some of the new trucks which are diesel-powered were sold 2 years ago. This must not be true otherwise the conclusion will break down.
Which one of the following is an assumption required by the auditor's reasoning?
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(A) All of the trucks that XYZ sold last year were diesel powered.
We know this. Why tell us again? (A) is out.
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(B) XYZ did not purchase any used trucks 3 years ago.
Does this imply those new trucks are not diesel-powered? (B) is out.
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(C) XYZ did not purchase any new trucks since it purchased the 20 trucks 3 years ago.
Trucks other than those 20 trucks 3 years ago are irrelevant.
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(D) None of the 20 trucks was sold before last year.
So this eliminates the possibility that the 20 truck were sold 2 years ago. Hang on to this.
[quote]v(E) XYZ no longer owns any trucks that it purchased more than 3 years ago.[/quo
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You don't own any more trucks. So you sold them all. Perhaps you sold them 2 years ago because they were diesel-powered that you don't like anymore. This matches our thought that weakens the argument. (E) is out.
Only (D) is left. D is our correct answer.