Q4 - Among the various models of Delta

[ohthatpatrick]

Question Type:
Sufficient Assumption

Stimulus Breakdown:
Conclusion: The power of a Delta's motor doesn't accurately predict how effective it will clean.
Evidence: Two Delta's might have the same power motor, but a difference in how efficiently their dust filtration system works.

Answer Anticipation:
We have to prove that "power of motor does NOT reliably indicate cleaning effectiveness". To prove such a claim, you would only need to demonstrate that "sometimes power X cleans to a level of Y effectiveness, other times power X does not clean to a level of Y effectiveness." You need a pair of Deltas that have the same power, but different cleaning effectiveness. What the evidence gave us was an example of two Deltas that have the same power, but different "dust filtration system" efficiencies. So the author is making a move from "different dust filtration system efficiencies" to "different cleaning effectiveness".

Correct Answer:
A

Answer Choice Analysis:
(A) Yes! This gives us the move we need from different dust efficiency to different cleaning effectiveness.

(B) So close, but we need to connect something to "how effectively it cleans". That idea is in our conclusion, but nowhere in our evidence.

(C) This says "if equal cleaning effectiveness, then same power motor". This is actually the opposite of what the author is trying to prove.

(D) The evidence dealt with un-equally efficient dust filtration. This answer choice is giving us a rule about equally efficient dust filtration. So we won't be able to apply this to the evidence and learn anything. Also, this is saying that the power of motor DOES reliably influence the cleaning effectiveness.

(E) This sounds more like the opposite of what the author is arguing. She is saying that "motor power is NOT an accurate predictor of cleaning effectiveness". This answer sounds more like "if you wanna know about cleaning effectiveness, check the motor power!"

Takeaway/Pattern: If we recognized that "how effectively it cleans" was a New Guy in the conclusion, then we would know that the correct answer MUST include that idea. That would quickly disqualify B. Understanding that the author was concluding "motor power is NOT a good indicator of cleaning effectiveness" would kill C, D, and E.

#officialexplanation

[kmewmewblue]

I am confused.
Is conclusion "The efficiency of dust filtration systems varies significantly,"?

Also, regarding general assumption question.
I've posted the same question on PT63, but I'm gonna ask again since I haven't gotten any response to it.
In assumption question, what I first do is spot the conclusion and find the new element which has not been mentioned in premises.
Then, I look at the answer choices, eliminate the choices which does NOT include the new element.
However, sometimes it is hard to find it in choices because the new element is paraphrased. When I encounter these, I get bumped and consume more time.
Should I not apply this strategy?

So, since I've mentioned that, in this question, if the conclusion is "The efficiency of dust filtration systems varies significantly," then the new element would be"the efficiency of dust filtration system." I can eliminate (B),(E) for this reason.
Then, I am stuck.

And, bottom line, I am not getting this question, anyways.

Any advice for improvement of my thinking, please!!!???
Thank you very much.

[daniel.g.winter]

Hey there,

This is my first attempt at explaining a question myself, but since I just took this PT yesterday and got this correct I figured I'd give it a shot.

The conclusion is actually the first sentence - "Among the various models of Delta vacuum cleaners, one cannot accurately predict how effectively a particular model cleans simply by determining how powerful its motor is." The line you cited is the support for this conclusion; however, there is an obvious gap between "the efficiency of dust filtration systems varies significantly" and "one cannot predict how effectively a particular model cleans."

Per your strategy, that is definitely a good way to look at it, but I would stay away from such concrete "rules" for certain question types. You want to understand WHY things are the way they are on the LSAT, so you can adjust to small tweaks in certain questions you might come across. So your strategy worked well in the past, but that doesn't guarantee it will work on every question, as this one is a great example of where it led you nowhere. That might have something to do with the fact that you misidentified the conclusion, but I would still make sure you understand that in this question, there is a gap between the premises and the conclusion, and your job is to bridge that gap. It's important to be able to clearly identify the gap in the logic and once you start doing that, assumption questions become quite a breeze.

Going through the answer choices, A is clearly the best answer for that job. It links up the efficiency of dust filtration systems with the effectiveness of cleaning. Even if you weren't sure at first, leave that as a contender and read the rest.

B is wrong because the conclusion is not about how powerful a motor is. We care about how effectively a certain model cleans, REGARDLESS of motor power.

C mentions cleaning effectively, but it never brings up dust filtration systems, and thus fails to bridge the gap.

D seems to go totally against the conclusion. Even if we knew how powerful the motor was, we cannot predict how well it will clean.

E is wrong because of the same reason as C.

Hope that helps! Again, this was my first stab at explaining. Hopefully one of the Geeks can refine my explanation if it wasn't spot on.

[kmewmewblue]

Your explanation was very tangible manner. I got it now. Thank you very much

[maryadkins]

Yes, great explanation. And just to add to your explanation of (C):

(C) says

clean effectively --> identical motor

while the stimulus says that with an identical motor, we still can't tell how effectively it cleans. (C) is flipping the logic here.

kmewmewblue, sorry to keep you waiting on a PT63 question! Hopefully someone will be on that soon. If not, please do email us or repost...