- Thu Feb 01, 2018 7:14 pm
#43424
Hi mokkyukkyu and mjb514,
This question is best approached by prephrasing and then looking for the one answer choice that matches (as opposed to considering how each answer choice would affect the argument). How do I know prephrasing is the best approach here? A Justify the Conclusion question presents an argument with a missing link and asks you to find it. I say all this to gently push back on "I understand why answer choice x is good, but why not y?" The right question is more like, "How did you know x?" because only the correct answer choice completes the argument and the other answer choices don't.
Premise 1
+
Missing Premise 2
=
Conclusion
In reading the stimulus, premise 1 says that if she sticks with her platform she will lose the young voters by a few percentage points but beat him by a bigger percentage among the older group, the rest of the voters. The conclusion is that if she sticks with the platform she wins the election. So the missing link must establish that...
losing the voters under 50 by a few percentage points but beating her opponent by a bigger percent for voters over 50 will result in more votes (i.e., winning the election).
We don't need precise math here, but we do need to know something about the relative number of voters under 50 and voters over 50. If there are more voters over 50, then she will automatically win even without knowing the percentage points.
To prove this to yourself (although please be aware that this proof is slow and not necessary to solve this question!), consider that there are 100 voters total. With her current platform, suppose she loses young voters by 2 votes and wins voters over 50 by 2 votes. If there are equal numbers in each group, there is a tie. She gets 24 votes and her opponent gets 26 votes for the younger group, while for the older group she gets 26 votes and her opponent gets 24. Both candidates would get 50 votes. But if Whalley wins the older group by a larger percentage AND there are more people in the older group, you can see how that would mean she would have to receive more total votes than her opponent. If there are 101 people and she wins the older group by 3 votes and there are 51 people in the older group (she wins this group 27 to 24) and still loses the younger group of 50 people by 2 votes: 24 to 26), then she wins with a total of 51 votes compared to 50 votes. [Note that if there are fewer voters over 50 but she wins that age group by enough percentage points she could still win the election, but that analysis isn't needed here because answer choice D is the only one that considers the relative numbers of voters in each group.]
Although I explained the math to honor a specific request, it is totally unnecessary. It's enough merely to realize that the number of people in each group affects how important it is to win a particular voting bloc. That's the same basic % versus # issue that LSAT tests in many of its Logical Reasoning questions.
So, we have the answer already before we look at the answer choices. We find the correct answer by looking for the answer that matches our prephrase. This is the best way to avoid getting distracted.
If you are still looking for an explanation of choice B, it's that we are not concerned with other ways that Whalley could change her platform to win the election. Considering the issues that matter to each does not get us from the premise about percentage points to the conclusion about winning the election.
