Logical reasoning PrepTest 140 · Section 3 · Question 19

Incorrect. Even if XYZ sold some non-diesel trucks last year, all of the trucks purchased 3 years ago could still be non-diesel. The argument just relies on the company selling off all their diesel trucks but none of the trucks from 3 years ago, thus confirming those trucks weren't diesel.

Incorrect. The conclusion is about the 20 new trucks purchased, so any other trucks purchased that year are out of scope.

Incorrect. Since the conclusion is about the 20 new trucks purchased 3 years ago, other new trucks purchased since then are out of scope.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen with Necessary Premise

Stimulus Summary:
3 years ago: XYZ bought 20 new trucks
Last year: No record of those trucks being sold; XYZ sold all diesel trucks
Conclusion: Those 20 new trucks 3 years ago weren't diesel

Answer Anticipation:
The argument here relies strongly on keeping the timeline straight, so we should be sure we understand it—that's why we laid our summary out the way that we did.

The premises are pretty strong here, so we should see how they intersect. Last year, all diesel trucks sold by XYZ were diesel, so any trucks still owned are not diesel. The stimulus also states that none of the trucks purchased 3 years ago were sold last year (or, at least, there's no records of them being sold). That doesn't, however, guarantee that the company still owns all of those trucks—they could have been sold 2 years ago! If any of those trucks were sold off 2 years ago, they could have been diesel trucks. Therefore, to conclude that the trucks weren't diesel, they must still be owned, and therefore they couldn't have been sold off before last year.

Additionally, the argument assumes that the reports are accurate/complete, so we should look for that.

Answer Explanation:
The argument relies on the diesel trucks all being sold last year when none of the 3-year-old new trucks were sold to conclude those trucks weren't diesel. However, if some of those trucks were sold 2 years ago, they could have been diesel trucks. This answer is necessary for the argument to work, so it's correct.

Key Takeaway:
The argument here relies strongly on a timeline—talking through things that happened 3 years ago and last year. When you note a hole in a timeline—here, there's no discussion of 2 years ago—there's a good chance that there's a flaw in ignoring things that happened that year! Short takeaway—always pay attention to the timeline.

Incorrect. Trucks outside of this group of 20 don't affect the argument that concludes something about these trucks. This answer is out of scope.