CR Weakening

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CR Weakening

by jerseygirl » Thu Sep 09, 2010 8:23 pm
Editorialist: Additional restrictions should be placed on driver's licenses of teenagers because teenagers lack basic driving skills. Even though drivers of age nineteen and younger make up only 7% of registered drivers, they are responsible for 14% of traffic fatalities.

Each of the following, if true, weakens the argument that teenagers lack basic driving skills EXCEPT:
(A) Teenagers tend to drive older and less stable cars than other drivers.
(B) Teenagers and their passengers are less likely to use seat belts and shoulder straps than others.
(C) Teenagers drive, on average, over twice as far each year as other drivers.
(D) Teenagers cause car accidents that are more serious than those caused by others.
(E) Teenagers are likely to drive with more passengers than the average driver.


____

The answer is:
[spoiler]D from LSAT Oct 97 / #26[/spoiler]

Can someone help with explaining this? I thought that B addressed the issue of basic driving skills less than D. The thinking was that teenagers could possibly be less likely to take precautions like use seat belts, but that doesn't necessarily mean they lack basic driving skills.

My issue with D is that if teenagers cause accidents more serious than those caused by others, it reflects basic driving skills moreso than use of seat belts.

IDK ...

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by reply2spg » Thu Sep 09, 2010 8:26 pm
I agree with D. Can you please chk C again. I hope C's wording is somehow messed up
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by jerseygirl » Fri Sep 10, 2010 3:03 am
Can you explain why D is correct>?

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by David@VeritasPrep » Fri Sep 10, 2010 5:48 am
As the spoiler in the post notes this is an LSAT question, but this is a good question to look at for the GMAT as well, it would be a higher level question for the GMAT.

This question asks you for the answer choice that DOES NOT WEAKEN the conclusion. The exact wording is "Each of the following, if true, weakens the argument that teenagers lack basic driving skills EXCEPT:"

Sometimes the question stem names the argument (which means the conclusion), if this happens then that is your main conclusion. In this case the question stem names the argument that will be weakened as "Teenagers lack basic driving skills."

This is actually a cause-and-effect type of statement. We know from the stimulus that teenagers are responsible for about twice as many fatalities (14%) as would be expected given the percentage of teenagers among total drivers (7%). There are a variety of possible causes for this fact. Teenagers could be driving the worst cars on the road, for example. Of these possible causes the argument seizes on one - teenagers lack basic driving skills.

One of the best ways to weaken cause and effect (and definitely the best on the GMAT) is to present an alternate cause. Therefore, the four incorrect answers to this problem should each present alternate causes and therefore weaken the conclusion that lack of basic driving skill is the cause. Remember this is an EXCEPT question so you are eliminating the answers that do weaken. The correct answer could strengthen or be irrelevant it just cannot weaken.

Choice A "Teenagers tend to drive older and less stable cars than other drivers" certainly presents an alternate cause for the high number of fatalities. The cars are to blame not necessarily the drivers.

Choice B "Teenagers and their passengers are less likely to use seat belts and shoulder straps than others" gives another very strong cause for more fatalities. Remember JerseyGirl that we are eliminating the answer choices that weaken and this one does weaken the idea that teenagers lack basic driving skills as the cause of fatalities. What they lack in this answer choice is common sense!

Choice C "Teenagers drive, on average, over twice as far each year as other drivers" is correctly worded "reply2" this one would also present an alternate cause. If the teenagers are on the road more they simply have more exposure to the possible accidents and fatalities.

Choice D skip for a second...

Choice E "Teenagers are likely to drive with more passengers than the average driver" also gives an alternate cause for the number of fatalities - specifically that there are more people to be hurt or killed in a crash because there are more passengers in the car.

Choice D is the EXCEPTION (and the correct answer) - this is the choice that does not weaken. WHY? Because "Teenagers cause car accidents that are more serious than those caused by others" is not another cause, but could in fact be another effect of the proposed cause - namely, teenagers lack basic driving skills and because of this they cause more serious accidents and more fatalities. So choice D does not necessarily weaken the conclusion the way that the other choices do.

Does that shed some light?
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by jerseygirl » Fri Sep 10, 2010 8:24 am
David@VeritasPrep wrote:As the spoiler in the post notes this is an LSAT question, but this is a good question to look at for the GMAT as well, it would be a higher level question for the GMAT.

This question asks you for the answer choice that DOES NOT WEAKEN the conclusion. The exact wording is "Each of the following, if true, weakens the argument that teenagers lack basic driving skills EXCEPT:"

Sometimes the question stem names the argument (which means the conclusion), if this happens then that is your main conclusion. In this case the question stem names the argument that will be weakened as "Teenagers lack basic driving skills."

This is actually a cause-and-effect type of statement. We know from the stimulus that teenagers are responsible for about twice as many fatalities (14%) as would be expected given the percentage of teenagers among total drivers (7%). There are a variety of possible causes for this fact. Teenagers could be driving the worst cars on the road, for example. Of these possible causes the argument seizes on one - teenagers lack basic driving skills.

One of the best ways to weaken cause and effect (and definitely the best on the GMAT) is to present an alternate cause. Therefore, the four incorrect answers to this problem should each present alternate causes and therefore weaken the conclusion that lack of basic driving skill is the cause. Remember this is an EXCEPT question so you are eliminating the answers that do weaken. The correct answer could strengthen or be irrelevant it just cannot weaken.

Choice A "Teenagers tend to drive older and less stable cars than other drivers" certainly presents an alternate cause for the high number of fatalities. The cars are to blame not necessarily the drivers.

Choice B "Teenagers and their passengers are less likely to use seat belts and shoulder straps than others" gives another very strong cause for more fatalities. Remember JerseyGirl that we are eliminating the answer choices that weaken and this one does weaken the idea that teenagers lack basic driving skills as the cause of fatalities. What they lack in this answer choice is common sense!

Choice C "Teenagers drive, on average, over twice as far each year as other drivers" is correctly worded "reply2" this one would also present an alternate cause. If the teenagers are on the road more they simply have more exposure to the possible accidents and fatalities.

Choice D skip for a second...

Choice E "Teenagers are likely to drive with more passengers than the average driver" also gives an alternate cause for the number of fatalities - specifically that there are more people to be hurt or killed in a crash because there are more passengers in the car.

Choice D is the EXCEPTION (and the correct answer) - this is the choice that does not weaken. WHY? Because "Teenagers cause car accidents that are more serious than those caused by others" is not another cause, but could in fact be another effect of the proposed cause - namely, teenagers lack basic driving skills and because of this they cause more serious accidents and more fatalities. So choice D does not necessarily weaken the conclusion the way that the other choices do.

Does that shed some light?
yes this makes sense. i'm finding that my brain flips statements, especially when it comes to weakening X questions.

for example, i correctly reasoned that the seat belt usage data point was an alternate cause, but i had this mental block that made me forget what i was looking for.

thanks!

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by reply2spg » Fri Sep 10, 2010 8:37 am
I didn't read drive in C. Sorry about that.

Thanks for the inputs David.

Sorry jerseygirl for not explaining, got stuck in hell lot of work :(
David@VeritasPrep wrote:As the spoiler in the post notes this is an LSAT question, but this is a good question to look at for the GMAT as well, it would be a higher level question for the GMAT.

This question asks you for the answer choice that DOES NOT WEAKEN the conclusion. The exact wording is "Each of the following, if true, weakens the argument that teenagers lack basic driving skills EXCEPT:"

Sometimes the question stem names the argument (which means the conclusion), if this happens then that is your main conclusion. In this case the question stem names the argument that will be weakened as "Teenagers lack basic driving skills."

This is actually a cause-and-effect type of statement. We know from the stimulus that teenagers are responsible for about twice as many fatalities (14%) as would be expected given the percentage of teenagers among total drivers (7%). There are a variety of possible causes for this fact. Teenagers could be driving the worst cars on the road, for example. Of these possible causes the argument seizes on one - teenagers lack basic driving skills.

One of the best ways to weaken cause and effect (and definitely the best on the GMAT) is to present an alternate cause. Therefore, the four incorrect answers to this problem should each present alternate causes and therefore weaken the conclusion that lack of basic driving skill is the cause. Remember this is an EXCEPT question so you are eliminating the answers that do weaken. The correct answer could strengthen or be irrelevant it just cannot weaken.

Choice A "Teenagers tend to drive older and less stable cars than other drivers" certainly presents an alternate cause for the high number of fatalities. The cars are to blame not necessarily the drivers.

Choice B "Teenagers and their passengers are less likely to use seat belts and shoulder straps than others" gives another very strong cause for more fatalities. Remember JerseyGirl that we are eliminating the answer choices that weaken and this one does weaken the idea that teenagers lack basic driving skills as the cause of fatalities. What they lack in this answer choice is common sense!

Choice C "Teenagers drive, on average, over twice as far each year as other drivers" is correctly worded "reply2" this one would also present an alternate cause. If the teenagers are on the road more they simply have more exposure to the possible accidents and fatalities.

Choice D skip for a second...

Choice E "Teenagers are likely to drive with more passengers than the average driver" also gives an alternate cause for the number of fatalities - specifically that there are more people to be hurt or killed in a crash because there are more passengers in the car.

Choice D is the EXCEPTION (and the correct answer) - this is the choice that does not weaken. WHY? Because "Teenagers cause car accidents that are more serious than those caused by others" is not another cause, but could in fact be another effect of the proposed cause - namely, teenagers lack basic driving skills and because of this they cause more serious accidents and more fatalities. So choice D does not necessarily weaken the conclusion the way that the other choices do.

Does that shed some light?
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by Target2009 » Tue Jan 04, 2011 10:14 pm
D must be ans

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by mundasingh123 » Fri Jan 07, 2011 3:24 am
David@VeritasPrep wrote:
Choice C "Teenagers drive, on average, over twice as far each year as other drivers" is correctly worded "reply2" this one would also present an alternate cause. If the teenagers are on the road more they simply have more exposure to the possible accidents and fatalities.

I got this quest right but just to analyze this question further, dont u think that in C , teenagers do not cause minor accidents because they possess basic driving skills.They cause serious accidents because of other reasons such as violation of traffic rules by others cars on the street.