LSAT 21 | Section 3 | Logical Reasoning: Q19

LR Question 19 Explanation

QUESTION TEXT: In the first decade following the founding of the…

QUESTION TYPE: Flawed Reasoning

CONCLUSION: It’s wrong to say that Labour gained more followers in its second decade than in its first.

REASONING: In each decade Labour’s followers increased five-fold.

ANALYSIS: I’ll use a numerical example. Suppose Labour started with 100 followers. After the first decade, these increase five-fold to 500. A gain of 400 people. Then after the second decade these 500 increase five-fold to 2500. A gain of 2000.

This is true for any starting number of followers. Labour will get five times the number of new members in the second decade.

So in the second decade the number of people gained was five times the number of people gained in the second decade, even though the percentage of people gained was the same.

___________

1. The dates are pretty clear: the first and second decades of Labour’s existence. You could look that up in an encyclopedia.
2. CORRECT. If the evidence is true then Labour did gain a larger number of followers in its second decade.
3. The evidence is quite relevant: it tells us how large Labour’s increase was.
4. Policy positions are irrelevant to how many people joined Labour.
5. It doesn’t matter how many elections were held. The main question is how many voters Labour had in any elections held during those decades.

Recap: The question begins with “In the first decade following the founding of the”. It is a Flawed Reasoning question. Learn how to master LSAT Flaw questions on the LSAT Logical Reasoning question types page.