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#9- Several major earthquakes have occurred in a certain

OriginalJane
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Hello David,

I chose D as the answer to this question because none of the other answers made sense. But even if the time between the changes in electric current and the occurrence of the quakes differed, why would this preclude the new detection method from being viable?

Thanks,

Amanda
Dave Killoran
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Hi Amanda,

This is an excellent question in terms of showing us how the test makers think, and how problematic it can be to generalize the conclusion, so let's break this one down.

The key, as is often the case in Weaken questions, is isolating the conclusion. In this case, the conclusion is that the new method "promises to aid local civil defense officials in deciding exactly when to evacuate" (italics added). That's a really specific decision they are talking about there. If (D) is true, then we have a timing issue, because (D) states that the length of time between the electric current change and the earthquake varies considerably. If that's the case, how will the officials know exactly when the people should evacuate? They won't (at least not exactly), and so the aid provided to officials is much less.

That conclusion wording is critical, because as you noted, does (D) undermine the viability of the detection method? No, it really doesn't; it just makes predictions based on the detection system somewhat difficult. So, I completely see where you were coming from, but unfortunately the test makers had a somewhat narrower idea to attack.

Great question, and one of those ones that is really useful for getting better going forward! Please let me know if that helps. Thanks!
Dave Killoran
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OriginalJane
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Hi David,

Thank you so much for your explanation. It really helped to clarify things. You and the rest of the folks at Powerscore really deserve a gold medal for all of the time you devote to helping us out beyond the publication of the books.

All the best,

Amanda
Dave Killoran
PowerScore Staff
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Aww, thanks Amanda! I really appreciate that and I'll pass that along to every else :-D

Thanks!
Dave Killoran
PowerScore Test Preparation

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maximbasu
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Hello,
I chose A as the correct answer while the correct answer was D.

I don't understand the relevance of the variation in length that D is talking about. The causality that the stimulus talks about is still happening. A on the other hand gives an alternative to the explanation; human error is partly to blame for the increase in earthquakes and this weakens the argument.

Thank you, Maxim.
Eric Ockert
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Maxim

The conclusion that you are trying to attack here is that "a new earthquake prediction method promises to aid local civil defense officials in deciding exactly when to evacuate various towns." The author never goes so far as to claim the earthquakes are causing these changes. It is a given fact that the changes in the electric current have so far been consistently present prior to these recent earthquakes.

So, using that language coupled with the Weaken question stem, your prephrase would be roughly: "Which answer choice suggests that maybe this new method will NOT help officials determine exactly when to evacuate people?"

Answer (D) certainly does this. If there is considerable variation in how long before an earthquake these changes occur, it could prove very difficult to know exactly when to evacuate people. This answer choice goes directly attacks the language of the conclusion.

Answer (A) on the other hand is dealing with an irrelevant consideration. If these changes to the electrical current precede every earthquake, officials could rely on that consistency even if they didn't fully understand why it occurred. The bottom line is that "understanding" is not really required for the officials to utilize the change's predictive powers, so the lack of understanding described in answer (A) is not necessarily a problem.

Hope that helps!
Eric Ockert
PowerScore LSAT/GMAT/SAT Instructor