LSAT 41, Logical Reasoning II, Q22, LSATHacks

LR Question 22 Explanation, by LSATHacks

QUESTION TEXT: Paleontologists recently discovered teeth from several…

QUESTION TYPE: Sufficient Assumption

CONCLUSION: Wooly mammoths on the island were smaller than average.

REASONING: Teeth of adult wooly mammoths found on the island are 25% smaller than average.

ANALYSIS: We’re looking for an assumption that makes the conclusion correct, if true. The wrong answers are at best necessary assumptions.

We need to show that tooth size is proportional to mammoth size.

___________

1. Not helpful. We already know that species are generally not completely uniform in size (e.g., Humans differ in height). This doesn’t let us conclude that smaller teeth = smaller mammoths.
2. This might be a necessary assumption, but it doesn’t let us draw a firm conclusion about the size of the mammoths.
3. Tempting, but in this case the stimulus clearly states that the teeth were from adult mammoths. In any case, simply knowing the teeth were adult teeth does not let us conclude anything about the size of the animals.
4. CORRECT. Yes, this tells us that smaller teeth = smaller mammoths.
5. This wouldn’t let us conclude that they were smaller in size. This isn’t even a necessary assumption: if the mammoths had one less tooth, would that invalidate our argument? (No)

Recap: The question begins with “Paleontologists recently discovered teeth from several”. It is a Sufficient Assumption question. Learn more about LSAT Sufficient questions in our guide to LSAT Logical Reasoning question types.

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