[求教]OG12 78超速吃罚单-大家总是解释为何选B，没有具体说明为何不选A

nightingale

Q78.

A recent report determined that although only 3 percent of drivers on Maryland highways equipment their vehicles with radar detectors, 33 percent of all vehicles ticketed for exceeding the speed limit were equipped with them. Clearly, drivers who equip their vehicles with radar detecters are more likely to exceed the speed limit regularly than are drivers who do not.

the conclusion drawn above depends on which of the assumotions?

A Drivers who equip their vehicles with radar detectors are less likely to be ticketed for exceeding the speed limit than are drivers who do not.
B Drivers who are ticketed for exceeding the speed limit are likely to exceed the speed limit reguarly than are drivers who are not ticketed.
C The number of vehicles that were ticketed for exceeding the speed limit was greater than the number of vehicles that were equipped with radar detectors.
D Many of the vehicels that were ticketed for exceeding the speed limit wre located more than once in the time period covered by the report.
E Drivers on Maryland highways exceeded the speed limit more often than diDd drivers on other state highways not covered in the report

首先我支持B选项可以说明问题，是符合题意的。但是请问A选项错在哪里呢？

如果说装了雷达的车更不容易因为超速而吃罚单，那结合题中条件，装了雷达的车吃了更多罚单，不是更应该证明装了雷达的车超速的次数比不装的车多得多么？
OG的解释是这个选项针对吃罚单的问题可能是真的，但与题中关于经常超速的问题不相关。我怎么觉得这个解释有点牵强呢？因为选项明明说的是are less likely to be ticketed for exceeding the speed limit，不是已经和超速联系起来了么？难道就是因为没有明确说在“相同次数”的超速情况下不容易吃罚单么？我怎么觉得这个思维还是不对呢？

希望大家理解了这个选项错误原因的给予解释。
谢谢！

azhuo

A说的是罚单（be ticketed，因为超速）

nightingale

因为超速吃罚单机率小+实际吃罚单多，不是更加可以推出实际超速多么？

我知道B是正着推的，很顺。
可是A可以逆着推啊，感觉也不无道理。

nightingale

有人帮忙解释一下不？

sdcar2010

When you negate A, as you did correctly, you get "Drivers who equip their vehicles with radar detectors are more likely to be ticketed for exceeding the speed limit than are drivers who do not." And this statement is consistent with one of the premise of the argument, therefore the argument still holds IF you follow the logic chain of the author because that's what the author claims! Whether or not the author's conclusion is right or wrong is not our concern for the assumption-type question. We have to treat the author's statements as correct. Since when you negate A, you do not weaken or refute the author's argument, the argument still holds.

nightingale

LS, thank you very much for your explanation, but I am afraid I cannot agree that we need to follow the logic chain of the author just because that's what the author claims.

The CR question asked "the conclusion drawn above depends on which of the assumptions", which means the assumption we selected cannot be ignored when getting the conclusion.  Without this assumption, there will be a gap between the premise and the conclusion of the argument.  In other words, if only based on the words provided in the argument, there is no "LOGIC" train.

Correct me if I am wrong.

Anyway, you provided a new point which I have not considered before.  Thanks very much, sdcar2010.

sdcar2010

In GMAT and LSAT CR questions, the stimulus normally gives a premise and a conclusion. It is paramount to remember, unless the question ask you to identify a faulty argument, the given premise and conclusion are treated as "right" in the sense that if the conditions in the premise is fulfilled, the conclusion is "logically" obtained.

That is the logic chain I am talking about. We only focus on the logic, not the "truth"of the whole argument.

When solving the CR question, it is essential to keep away from adding your own judgement or evaluation of the statements. Focus on the reasoning part.

Therefore, when negating A, the argument still holds because negating A won't affect the "logic" used in the stimulus since it only repeats the premise.

sdcar2010

Assumption means "untold" premise. Thus, when the speaker makes the argument in the stimulus, he assumes the "untold" premise is correct.  In that sense, his argument has correct logic chain although he does not specifically STATE the untold premise.

As a test taker, you are supposed to find out which one of the answer choices is the untold premise that the author takes for granted.

nightingale

Still a little confused, but I noticed one difference between A and B.

If we negate A, the argument might hold or not.
If we negate B, the argument definately cannot hold.

It is the difference between the sufficiency and necessity.
So can we say that the assumption this question required is a necessary condition, rather than a sufficient evidence, to reach the conclusion?

sdcar2010

Show me your reasoning why after negating A, the argument might not hold.

Remember, no outside assumptions or opinions.  Just follow the logic presented in the stimulus.