Conclusion-Sabado Domingo is a true prodigy, able to recognize when any single instrument in his orchestra is even a bit out of tune.

So we need to find that answer choice which proves Sabado's fault finding expertise.

(A) During the test, the orchestra was arranged in a traditional arrangement, similar to the arrangement in which they would be seated in a classical concert.--The arrangement of equipment's doesnt matter as long as sabado is correctly able to identify the faulty tune/instrument
(B) Domingo did not mistakenly label any of the orchestra’s in-tune performances as out of tune.-It reinforces Sabado's skill set by stating that not only he got everything right but also didnt get anything wrong-Correct answer
(C) Many of the musicians who intentionally played out of tune as part of the test have played perfectly in tune in every concert for the last ten years.-The musicians performance doesnt affect Sabado's performance/skills
(D) The instruments played out of tune were all played at a pitch exactly one half-step lower than the true pitch.--The pitch played doesnt affect Sabado's performance/skills
(E) Because the test was performed in an empty concert hall, the acoustics of the concert hall differed somewhat from those of a concert hall populated by an audience.-empty concert hall doesnt affect Sabado's performance/skills

(A) During the test, the orchestra was arranged in a traditional arrangement, similar to the arrangement in which they would be seated in a classical concert.
The arrangement is not the issue in this question.

(B) Domingo did not mistakenly label any of the orchestra’s in-tune performances as out of tune.
Correct, if he didn't label anything wrong, means that his accuracy is the best, and support the argument

(C) Many of the musicians who intentionally played out of tune as part of the test have played perfectly in tune in every concert for the last ten years.
The issue is not about the intention of the musicians in playing out of tune.

(D) The instruments played out of tune were all played at a pitch exactly one half-step lower than the true pitch.
Tempting, however the question is about the accuracy to find the instrument that is out of tune.

(E) Because the test was performed in an empty concert hall, the acoustics of the concert hall differed somewhat from those of a concert hall populated by an audience.
The place is not the issue

I don't even know how to explain...by POE, I eliminated all but B...B seems the most logical one.

This is a strengthener/supporter question , so the correct option must strengthen the conclusion and conceal any scope for attacking the reasoning used to arrive at the conclusion and none except (B) does it perfectly...
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The young orchestral conductor Sabado Domingo is a true prodigy, able to recognize when any single instrument in his orchestra is even a bit out of tune. In a recent test, an orchestra played a hundred selections from different well-known classical pieces; in approximately half of the selections, exactly one instrument would be played slightly out of tune. In every instance in which an instrument was played out of tune, Domingo pointed out that the orchestra was out of tune, and correctly identified the instrument at fault.


But isn't b repeatation of last line of the passage? It is already given that he pointed out every error correctly.

Also, can't we say that the players did not perform those mistakes in all other concerts so sabado domingo did not merely guess based on his prior experience but truly identified the errors

B doesn't repeat what's mentioned in the passage.
It is just stating the same thing in different words.

For example: There are 2 ways in which you can get the correct answer for a GMAT question:
1. Find the correct answer.
2. Eliminate the wrong choices.
Now, both the options help us in finding the correct answer but the meaning/approach is different in both.
Similarly the prodigy used 2 different ways, first as per the passage and second as per the option B.

Hope it helps.

A. This one got me thinking, if he was a true prodigy he'd be able to recognize an out of tune instrument regardless of seating arrangement. While this may not be the right way to approach the answer choice itself, it got me thinking about the other implications of his being a prodigy. In some ways this might weaken the argument in the sense that he can only identify an out of tune instrument under very specific parameters. For this reason I eliminated A.

B. Some people say that this one is a repetition of the statements in the original argument, but that is not the case. This is the correct answer. The way I thought this answer choice was that it introduced the possibility of false-negatives or false-positives and addressed that issue. The passage stated that in about half of the selections played (roughly fifty) that he correctly identified the instrument that was out of tune, which is a true-positive, but makes no statement about a false-positive. What if it were the case that in the other fifty selections played (in which all instruments were played in tune) Domingo said there was an instrument that was out of tune? Then he wouldn't be quite the prodigy. While this wasn't my first thought while reading through the passage it does fill in that final point that we can use to conclude that yes, Domingo is in fact a prodigy. That is why answer B is correct.

C. Regardless of whether the musicians were playing out of tune intentionally or unintentionally, the end result is the same; if Domingo can point it out, he is correct. The musician's skill has nothing to do with it.

D. A full half step down is a largely noticeable difference. I'm not sure if this would make sense to those who don't have a bit of experience in tuning instruments or with physics but for those who have no idea about how music works, I don't feel this is a very fair answer choice. The only reason I crossed this one off was because a half step is very, very noticeable and would therefore speak nothing of Domingo's ability to pinpoint an out of tune instrument.

E. The logic for eliminating this answer choice is similar to the logic behind crossing out answer A; this doesn't speak to Domingo's ability as a prodigy as if he were truly a prodigy he should be able to pick out an out of pitch instrument from any location with any background.

This was my reasoning for all the answer choices. Let me know if you agree or not!

This type of CR question is extremely hard for me. After reading the statement, my feeling is that the conclusion is already strengthen by the "Domingo pointed out that the orchestra was out of tune, and correctly identified the instrument at fault".
And it is very hard for me to find the correct answer.
Can anyone give me some advice on this ? Thank you very much!

Option B exactly repeates the facts in the last line of the passage. How does it strengthen anything? This is a very vague question with a very weird OA. I am not confused. I just do no agree!!

Option (B) is NOT the same as that given in the argument. Please note:

Conclusion:
Domingo is a true prodigy, able to recognize when any single instrument in his orchestra is even a bit out of tune.

The implication is clear - when any single instrument is a bit out of tune, he will recognise. Also, if no instrument is out of tune, he will know that everything is fine. If every time the orchestra plays and he declares that something is out of tune, it does not establish him as a prodigy. He needs to know when something is out of tune and when it is not.

The argument tells us that in a test, 50% of the times, one instrument was played out of tune. In every instance in which an instrument was played out of tune, he pointed out the instrument that was out of tune. So 50% of the times, he correctly identified that an instrument was out of tune and also which instrument was out of tune.
This is good. But what will help further establish that he is a prodigy and that he is extremely accurate?
That every time no instrument was out of tune, he said that no instrument is out of tune. He judged the other 50% correctly too.

What if of the rest of the 50% times when every instrument was played in sync, he still said that something was out of tune? Then can we say that he judges correctly? No.

Option (B) gives us this flip side
(B) Domingo did not mistakenly label any of the orchestra’s in-tune performances as out of tune.

Hence (B) strengthens our conclusion.
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