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by mttorii » Wed May 28, 2008 2:14 pm
Reading skills among high school students in Gotham have been steadily declining, which can only be the result of overcrowding in the schools.

Which of the following, if true, most seriously weaken the argument above?

A) The high school system in Gotham succeeds in giving students a good education at considerably less cost than do most system.
B) Several cities have found that overcrowding in the schools is not always associated with lower reading score.
C) Gotham schools have a greater teacher-to-student ratio than most other schools.
D) Student's reading skills have not declined in other cities where the high schools are just as crowded as those of Gotham.
E) Schools are not overcrowded in many cities where high schools reading scores have declined more than they have in Gotham.
Source: — Critical Reasoning |

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by wawatan » Wed May 28, 2008 2:28 pm
it's really between D and E. I can't rule out D but E has more of a valid reason. If classrooms aren't crowded but skills are still declining, then overcrowding CANNOT be the reason for the decline in reading skills. if i really have to choose,i'd pick E.

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by Stuart@KaplanGMAT » Wed May 28, 2008 3:59 pm
wawatan wrote:it's really between D and E. I can't rule out D but E has more of a valid reason. If classrooms aren't crowded but skills are still declining, then overcrowding CANNOT be the reason for the decline in reading skills. if i really have to choose,i'd pick E.
E is correct.

The problem with D is that it interprets the argument backwards. The author is arguing that overcrowding caused the low scores, but not that overcrowding ALWAYS causes low scores.

To weaken an argument that A must have caused B, we look for either another cause for B or a case in which B occured but A didn't; the latter is what we get in (E).

As you note, (E) ensures that something other than overcrowding can cause lower scores, which makes us doubt the author's argument that it's the only possible cause.
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by netigen » Wed May 28, 2008 5:18 pm
Question stem is very clear that author thinks that overcrowding is the only possible reason that the reading skills have gone down. This means that the author has considered and discounted all other possibilities and he thinks that none of those hold in this case.

"which can only be the result of overcrowding"

The statement will be MOST weakened if we show that there are other causes of the drop in reading skill.

E is the statement that tell us there are some other causes for the drop.

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by loki.gmat » Wed May 28, 2008 11:05 pm
IMO D.

If u closely analyze E, it clearly says that overcrowding is not an issue in schools belonging to many cities. However, it doesnot negate the possibility of overcrowding in Gotham. For eg, assuming that in-efficiency of teachers in many cities (apart from gotham) is the actual reason behind decline of reading skills. Now there is a possibility that the teachers in gotham are efficient but the overcrowding is to such an extent that the efficiency of the teachers is negatively affected & hence the decline in the reading skills of the students in gotham. Option E doesnot rules out this possibilty.

Option D suggest a level playing field as far as no of students is considered. Hence there might be multiple reasons (apart from overcrowding) for decline in reading skills of the students in gotham such as inefficient teachers, low iq level of students etc.

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by mttorii » Thu May 29, 2008 1:53 pm
Thanks for the explanations.

Does anybody know if this kind of question is common in an official test?

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by Stuart@KaplanGMAT » Thu May 29, 2008 7:56 pm
Weakening is by a large margin the most common question type in critical reasoning.

Causal arguments are also very common.
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by khanshainur » Tue May 10, 2016 5:08 am
i think it's E