PrepTest 124

Incorrect. The uniformity of tooth or overall size doesn't affect the argument—it's the uniformity of the relationship between those two that's relevant.

Incorrect. This tooth wear would presumably affect mammoths of both populations, and it's unclear how this would justify the jump between tooth size and overall body size. If anything, this is more of a necessary assumption for the argument, ruling out one thing that could throw the relationship off.

Incorrect. In this case, they're of adult wooly mammoths, so these other teeth are out of scope.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen with Sufficient Premise

Stimulus Summary:
Adult mammoth teeth that were smaller than average were found on an island. Thus, assuming the teeth are representative, these mammoths were smaller on average than other mammoths.

Answer Anticipation:
Note that there's a qualification on the conclusion—it's predicated on the teeth being found being representative of the adult mammoth population overall. Without that note, there would be a sampling flaw in this stimulus; with it, there is no sampling flaw, so we need to look elsewhere for the gap in the reasoning.

For Strengthen with Sufficient Premise questions, we usually want to start by looking for concepts in the conclusion that weren't mentioned in the premises. In this case, we find one—the overall mammoth size. The premises are about only the teeth of the mammoths on this island. As such, the argument is jumping from the size of the teeth to the overall size.

It's just as plausible, based on the information presented, that the mammoths were average sized, or even bigger than average, but with smaller teeth! For this argument to work, it needs to be established that tooth size is a reliable indicator of adult mammoth size. Let's look for that answer.

Answer Explanation:
This answer establishes that measuring tooth size can always allow a conclusion to be drawn about the overall size of the wooly mammoth it came from. That justifies the jump made in the stimulus, so this is the correct answer.

Key Takeaway:
In Strengthen with Sufficient Assumption questions, always be on the lookout for new concepts in the conclusion. When one is present, it'll need to be connected to a related term in the premise in order to justify that conclusion, making your anticipation both specific and much easier than if you're going in blind!

Incorrect. It's the size of the teeth that's relevant, not their number or variety.