Critical Reasoning

"The Ivory-billed Woodpecker has been considered extinct for the past several decades. Recently, researchers claim to have found a pair of Ivory-bills in Arkansas. Their best evidence is video that shows a large woodpecker flying away from the camera. The bird has the characteristic large white patches on the trailing edge of the wings. This is one of the factors that distinguishes Ivory-bills from the closely-related Pileated Woodpecker. However, skeptics of the discovery argue that some abnormal Pileated birds can have extra white on the wing and that the bird in the video is most likely an abnormal Pileated. They conclude that the evidence offered for the existence of a living Ivory-billed woodpecker has been overstated and that the species is probably still extinct."

Which of the following, if true, would most strengthen the skeptics' conclusion?

A) Before this discovery, the last reported Ivory-billed woodpecker was seen in Louisiana, not in Arkansas.

B) In the area where the video was shot, researchers listened for the distinctive "double-tap" drumming sound made exclusively by Ivory-billed woodpeckers, but did not hear the sound.

C) The first person to see the reported Ivory-billed woodpecker and the photographer who shot the footage were not scientists.

D) Of the five key features used to identify Ivory-billed woodpeckers, only the extra white on the wing was seen and this feature also occurs on abnormal Pileated woodpeckers.

E) The bird in the video is clearly seen using the motion of the wing that is characteristic of both the Ivory-billed and the Pileated woodpecker.



Source GMAT for Dummies, Wiley, 2006.

Here is one of the first Critical Reasoning questions that I wrote back in 2005 while contributing to the "GMAT for Dummies" book. I did not see it posted anywhere yet and that makes it almost as good as new. I think those who are very serious about the GMAT are probably not familiar with this book as it is not nearly as in-depth as the other materials we use... However, there are some questions in there that most people have not seen, so why not try this one? Good luck!

David@VeritasPrep wrote:"The Ivory-billed Woodpecker has been considered extinct for the past several decades. Recently, researchers claim to have found a pair of Ivory-bills in Arkansas. Their best evidence is video that shows a large woodpecker flying away from the camera. The bird has the characteristic large white patches on the trailing edge of the wings. This is one of the factors that distinguishes Ivory-bills from the closely-related Pileated Woodpecker. However, skeptics of the discovery argue that some abnormal Pileated birds can have extra white on the wing and that the bird in the video is most likely an abnormal Pileated. They conclude that the evidence offered for the existence of a living Ivory-billed woodpecker has been overstated and that the species is probably still extinct."

Which of the following, if true, would most strengthen the skeptics' conclusion?

A) Before this discovery, the last reported Ivory-billed woodpecker was seen in Louisiana, not in Arkansas.

B) In the area where the video was shot, researchers listened for the distinctive "double-tap" drumming sound made exclusively by Ivory-billed woodpeckers, but did not hear the sound.

C) The first person to see the reported Ivory-billed woodpecker and the photographer who shot the footage were not scientists.

D) Of the five key features used to identify Ivory-billed woodpeckers, only the extra white on the wing was seen and this feature also occurs on abnormal Pileated woodpeckers.

E) The bird in the video is clearly seen using the motion of the wing that is characteristic of both the Ivory-billed and the Pileated woodpecker.



Source GMAT for Dummies, Wiley, 2006.

Here is one of the first Critical Reasoning questions that I wrote back in 2005 while contributing to the "GMAT for Dummies" book. I did not see it posted anywhere yet and that makes it almost as good as new. I think those who are very serious about the GMAT are probably not familiar with this book as it is not nearly as in-depth as the other materials we use... However, there are some questions in there that most people have not seen, so why not try this one? Good luck!

I am confused between D and E.

IMO E

I'd go with D.

IMO D

because out of the 5 characteristics only the white wing was seen that can occur on both the species of woodpecker. So, ultimately it states that the bird seen was not the Ivory Woodpecker.

wats d OA??

OA = B

The OA is D.

The conclusion is that "the evidence offered ....has been overstated" and therefore the "species is probably still extinct."

Answer choice D goes to directly to the evidence (as gsinghal said in a prior post). The only solid evidence in favor of the ivory-billed is presence of the large white wing patches and answer choice D makes this evidence much less decisive by indicating that the large patches can be on pileated as well.

Choice B is deceptive because hearing the sound would make very good evidence, but not hearing the sound does not undermine the visual evidence like choice D does.

David@VeritasPrep wrote:The OA is D.

The conclusion is that "the evidence offered ....has been overstated" and therefore the "species is probably still extinct."

Answer choice D goes to directly to the evidence (as gsinghal said in a prior post). The only solid evidence in favor of the ivory-billed is presence of the large white wing patches and answer choice D makes this evidence much less decisive by indicating that the large patches can be on pileated as well.

Choice B is deceptive because hearing the sound would make very good evidence, but not hearing the sound does not undermine the visual evidence like choice D does.

David, i always like your CR, but do you think its a bit long for a real test CR? if the real CR in test are as long as the CR you posted, i am a bit worried

It is on the long side to be sure. If they were all this long you might have some concerns but you can handle one or two that are this length. I also think that this one makes up for the length by being fairly understandable.

For comparison, question 82 (of 82) in the 1st edition of the OG verbal review (page 142) is more than 30 words longer than "ivory-billed woodpecker" and the answer choices are much longer as well.

Do you have that book? Should I post that question? I do not see that it has ever been posted on BTG, although it is an OG question? It is a tough one....

David, could you please post the other CR question you are referring to?

Thanks
Deeyah

I just posted the bold faced OG question!

David

Hi David,

Could you please explain why E is wrong?

Thanks.

Answer choice E does indeed mention something that is true of both woodpeckers and is not unique to ivory billed woodpeckers - this could weaken under the right circumstances.

However, in this problem the case in favor of the ivory-billed was not relying on the wing motion of the woodpecker, but on the large patch of white on the wing. Answer choice D directly undermines that main evidence of the large white patches on the wing so this is the correct answer.

Hope that helps!

David@VeritasPrep wrote:Answer choice E does indeed mention something that is true of both woodpeckers and is not unique to ivory billed woodpeckers - this could weaken under the right circumstances.

However, in this problem the case in favor of the ivory-billed was not relying on the wing motion of the woodpecker, but on the large patch of white on the wing. Answer choice D directly undermines that main evidence of the large white patches on the wing so this is the correct answer.

Hope that helps!

Thanks so much for replying.

But choice D partially just mentions what is already given in the argument. The argument already says "some abnormal Pileated birds can have extra white on the wing". Choice E provides us a new evidence that supports skeptics point of view that there are reasons to believe that the bird is in fact a Pileated woodpecker. Shouldn't E be a better choice in this case?

Thank you for pointing that out. You are absolutely correct. This should have been edited so that the stimulus did not say that about the wing patches, then D would be new information!!

This has been in print for several years -- we should have had you edit!

David

David@VeritasPrep wrote:Thank you for pointing that out. You are absolutely correct. This should have been edited so that the stimulus did not say that about the wing patches, then D would be new information!!

This has been in print for several years -- we should have had you edit!

David

Hi Dave,

I am somehow not convinced with D. Option D clearly states that 'white patches' can appear on both ivorey billed and abnormal pileated. So there is a possibility that the evidence could still point to ivory bill, in which case Option D will weaken skeptics argument. !!

Option B on the other hand says that 'ivory bill' failed on the other evidence too - (i.e.) peculiar sound. Also please note that the evidence offered in the passage is 'video' and the characteristics large white patch is one of the observations.

Can you explain? Thanks