#23 - In modern "brushless" car washes, cloth strips called

[moshei24]

After analyzing this question for a LONG time, I don't see how choice C can be proven factual from the stimulus. I see how it's most likely true, but I don't see how it's fully supported. And according the PowerScore books, most like true answer are wrong. Can someone please explain this question to me?

Thanks,
Moshe

[Justin Eleff]

You're right, I suppose, that we can't absolutely prove the truth of (C) by referencing the stimulus alone. It's possible in theory that pre-modern car washes essentially scratched EVERY car, and while modern car washes are BETTER, they still scratch MOST cars, even ones with older, harder-to-scratch finishes. (As a practical matter, of course, if pre-modern car washes had scratched every car or even most cars, there would be no such thing as modern car washes; the whole car-washing industry would have died when outraged customers drove their newly-scratched cars home in anger, cursing and swearing off car washes forever.) So, no, we can't prove that the percentage of those cars with older, harder-to-scratch finishes that nonetheless get scratched by newer, easier-on-finishes brushless car washes is less than 50 ... so (C) cannot be absolutely established, and you're technically right. That said, there's no point in discussing this further, as (C) is clearly the answer that comes closest to being provable, and the question stem itself asked for the answer that was MOST STRONGLY supported, not ABSOLUTELY supported. (C) is supported both by the fact that older finishes = harder to scratch and by the fact that mitters = better at not scratching even newer finishes. The better mitters are at not scratching what's easy to scratch, the even-better-than-that they must be at not scratching what's harder to scratch, so the chances of most cars with older finishes emerging with scratches from modern car washes would seem to be essentially (though not absolutely) nil.

[moshei24]

Right. That's what I was thinking - it says most supported. My issue was that the course says that "most supported" falls under the category of "must be true." The course doesn't distinguish between the two, but this question and many other ones clearly show a difference between a question that asks which one must be true and which one is most supported. In fact, what would be a correct answer for "most supported" might not be a correct answer for "must be true." So how do I go about dealing with those types of questions? The course says do one thing, but that wouldn't necessarily work for that question. I'm not trying to attack the course, but it seems that part of what it teaches could lead to confusions in these types of questions. The course specifically says that for must be true TYPE questions, answers that are most likely true are wrong. In this question, and many other "most supported" questions, answers that are most likely true are correct.

Unless there's a difference between "likely to be true" and "almost definitely true." The course uses the term "likely to be true," but then it also says the answer must be true. So I'm confused as to how those techniques apply to these types of questions.

Help? Thanks!

[Joshua Kronick]

As a practical matter, something like this is so incredibly rare I wouldn't worry about having to "learn how to adjust to it," and in fact, as mentioned above by Justin, the other four answers are clearly losers.

[moshei24]

But, I think that often the "most supported" questions are just that - most supported. They usually aren't questions that can be mechanically proven like "must be true" questions. Am I just imagining that? Or are "most supported" questions often correct when they are most likely true, while "must be true" questions would be wrong if they were most likely true?

Thanks!

[karen_k]

Hi,

On 23, I narrowed down my choices to A and C but neither seemed that great to me. On A, the "more cars on the road [...] than today" made me wary of that choice but I wasn't sure about C either because of the word "visible" since the stimulus never mentioned anything about scratches being visible. I'd greatly appreciate any clarification! Thank you!

[Emily Haney-Caron]

Hi Karen!

Im glad you got it down to A and C on 23. A is wrong because we just don't know one way or the other; the brushes scratched more, but the finish was more resistant to scratching than the finish today is, so it is impossible to know whether the net result was more scratches or not. For C, we can assume that modern car washes don't scratch current car paint to bits (or they wouldn't exist), and the older finish was even harder to scratch. C isn't a perfect answer, but it is definitely the best answer.

Hope that helps!

[Leela]

Hi, could someone please explain why answer choice E is wrong? I narrowed to C and E, but both seemed to be contenders based on

Mitters are easier on most cars' finishes than brushes are.

from the stimulus.

C was a contender for me, because if the mitters are easier on most cars and we don't know what proportion we have of new/old cars, it would seem that they wouldn't have replaced the brushes if they produced scratches on old cars.

E was a contender for me, because we know that the new clear-coat is found on many cars today. Though, we don't know what the proportion of new/old cars there are. If the mitters are easier on most cars' finishes, it seems to also make sense to me that more cars in use today have the clear-coat finish. Is this weaker than C, because more cars with the clear-coat finish doesn't necessarily create the "easier on most cars' finishes" found in the stimulus?

[Adam Tyson]

We can't conclude anything about the proportion of cars that have clear-coat finishes, leela. We only know that mitters are easier on the finishes of most cars than are brushes, and that clear-coat finishes are more easily scratched than older ones. If mitters are better on the clear-coat finishes, and older finishes are less likely to scratch, then mitters are probably also fine for older cars (at least so far as scratching them is concerned). That's how we can get to answer C - it's unlikely that the gentler mitters would scratch the more durable older finishes.

For all we know, 99% of all the cars on the road have those older finishes! Clear-coat is new and found on "many" cars, but "many" gets us nowhere near "most."

[Leela]

Thanks, Adam! I appreciate the clarification and now understand why E is a clear loser.