Critical Reasoning

Why is E correct and A and D wrong?

Premise:
There has been a decline in auto-related hospitalizations.
Conclusion:
Air bags and seat belts have made Vorland's automobiles safer for drivers involved in accidents.

Apply the NEGATION TEST.
When the correct answer choice is negated, the conclusion will be invalidated.

E, negated:
There has been a steady decline in the number of drivers involved in accidents.
Here, the decrease in the number of hospitalizations is due to a decrease in the number of ACCIDENTS, invalidating the conclusion that AIR BAGS and SEAT BELTS have caused the decrease in the number of hospitalizations.
Since E invalidates the conclusion, E is the correct assumption: WHAT MUST BE TRUE for the conclusion to be valid.

The correct answer is E.

A, negated:
The citizens of Vorland do not obey all local and national speed limits.
D, negated:
There has been at least one increase in speed limits on Vorland's highways.
These negations suggest that the number of accidents might have INCREASED, potentially STRENGTHENING the conclusion that air bags and seat belts have helped drivers in these accidents avoid hospitalization.
Since these negations do not invalidate the conclusion, eliminate A and D.

Don't you think the conclusion is the last sentence - "Clearly, the new regulations have made Vorland's automobiles ..... who are involved in accidents" and the two statements before that are the premise?

girishj wrote:Ten years ago the country of Vorland adopted new automobile safety regulations requiring airbags and better seat belts in all new automobiles. Since then, the annual number of drivers and passengers hospitalized overnight or longer for injuries sustained in automobile accidents has steadily declined. Clearly, the regulations have made Vorland's automobiles safer for drivers and passengers who are involved in accidents.

Which of the following is an assumption on which the argument depends?

(A) The citizens of Vorland generally obey all national and local speed limits.

(B) Of the patients treated at hospitals in Vorland, the percentage treated being treated for injuries sustained in automobile accidents has decreased in the past ten years.

(C) The safety improvements required by the regulations have not significantly affect the price of new automobiles.

(D) There has been no increase in speed limits on Vorland's major highways over the past ten years.

(E) Over the past ten years there has not been a steady decline in the annual number of drivers and passengers involved in automobile accidents in Vorland.

Generally in assumption questions there is a gap between the premises and the conclusion. The argument therefore depends on some assumption for filling that gap.

Premise: Hospitalizations of people sustaining injuries in automobile accidents have declined since the adoption of the regulations.

Conclusion: The regulations have made Vorland's automobiles safer for drivers and passengers who are involved in accidents.

Gap: There is no clear connection between the regulations and the decline in injuries requiring hospitalization. The regulations may be the cause of the decline, but something else could be the cause. So the argument depends on assumptions that are related to the connection between the regulations and the reduction in injuries requiring hospitalization.

(A) This is not necessary for connecting the regulations to the decline in hospitalizations. The regulations could have an effect whether people obey the limits or not.

(B) This answer sounds GREAT, and if you are looking for a "sounds right" answer you might choose this one. So this answer choice shows why you won't get CR questions right by choosing "sounds right" answers, as this answer choice has zero effect on the argument.

If hospitalizations for automobile accident related injuries have declined, then they have declined whether they have declined or increased as a percentage of total hospitalizations.

(C) The GMAT loves to give you answer choices that voice thoughts people commonly have regarding certain situations. This answer choice does that, as there may be a cost to the regulations, but the cost is irrelevant to an argument using the decline in injuries as evidence that the regulations have increased safety.

(D) Hmm. Speed limits seem related to the argument, but what this answer choice says is not related to the gap between the decline in injuries and the conclusion that the regulations are the cause.

(E) This is it. The argument depends on the assumption that the reduction in injuries is the result of the regulations. In other words, the argument depends on the assumption that cause of the decline in injuries is not a decline in crashes.

The correct answer is E.

girishj wrote:Don't you think the conclusion is the last sentence - "Clearly, the new regulations have made Vorland's automobiles ..... who are involved in accidents" and the two statements before that are the premise?

Correct.
At its core, this is a CAUSAL argument.
In a causal argument, A and B are observed together, and the CR concludes that A caused B.
Here, observed together are A (new regulations requiring air bags and seat belts) and B (a decrease in the number of auto-related hospitalizations).
As a result, the argument concludes that A caused B -- that the required air bags and seat belts have CAUSED the decrease in the number of auto-related hospitalizations.
In my post above, I paraphrase this causal relationship.

Thanks Mitch and Marty. Your replies have been extremely helpful. I have posted few other questions in SC, CR and RC. May I request you'll to provide replies for those as well. My GMAT is just around the corner. Thanks in advance

GMATGuruNY wrote:Premise:
There has been a decline in auto-related hospitalizations.
Conclusion:
Air bags and seat belts have made Vorland's automobiles safer for drivers involved in accidents.

Apply the NEGATION TEST.
When the correct answer choice is negated, the conclusion will be invalidated.

E, negated:
There has been a steady decline in the number of drivers involved in accidents.
Here, the decrease in the number of hospitalizations is due to a decrease in the number of ACCIDENTS, invalidating the conclusion that AIR BAGS and SEAT BELTS have caused the decrease in the number of hospitalizations.
Since E invalidates the conclusion, E is the correct assumption: WHAT MUST BE TRUE for the conclusion to be valid.

The correct answer is E.

A, negated:
The citizens of Vorland do not obey all local and national speed limits.
D, negated:
There has been at least one increase in speed limits on Vorland's highways.
These negations suggest that the number of accidents might have INCREASED, potentially STRENGTHENING the conclusion that air bags and seat belts have helped drivers in these accidents avoid hospitalization.
Since these negations do not invalidate the conclusion, eliminate A and D.

Dear GMATGuruNY

I think option A and option D do not have any impact on the argument's conclusion. I think the regulations have to do nothing with
a) local and national speed limits
b) increase/decrease in speed limits

The argument has clearly noted that the country of Vorland adopted new safety regulations requiring air bags and better seat belts in all new automobiles. These regulations, in my honest opinion, have nothing to do with the speed of automobile.
X
So, can I reject these two choices ( A and D) as "Out of Scope"

Thank You in advance

a_new_beginning wrote:I think option A and option D do not have any impact on the argument's conclusion. I think the regulations have to do nothing with
a) local and national speed limits
b) increase/decrease in speed limits

The argument has clearly noted that the country of Vorland adopted new safety regulations requiring air bags and better seat belts in all new automobiles. These regulations, in my honest opinion, have nothing to do with the speed of automobile.
X
So, can I reject these two choices ( A and D) as "Out of Scope"

Thank You in advance

Hi a_new_beginning.

Rejecting answer choices as out of scope is a method that is often misused.

In this case, while the conclusion is that the reduction in hospitalizations is the result of the air bag and set belt regulations, ANYTHING that could affect the number of hospitalizations is within the scope of the argument.

Clearly, changes in driving speed could increase or reduce the number of crashes, and thus affect the number of hospitalizations.

So driving speed is within the scope of this argument.

To see with crystal clarity why, consider the effect had D said, "There has been no decrease in the speed limit ..."

A negation of that statement would be, "There has been a decrease in the speed limit ..."

Were a decrease in the speed limit to result in slower driving speeds, that decrease could result in a decrease in crashes and in related hospitalizations. So the argument depends on the assumption that there has not been a decrease in the speed limit, because if there were, then the speed limit decrease, rather than the new regulations, could be the cause of the reduction in hospitalizations.

So driving speed and speed limits are in fact related to the conclusion of this argument.

Generally speaking, in order to consistently get right answers to CR questions, you have to go beyond using simple methods, such as ruling things out of scope because they discuss things not discussed in the arguments, to using higher level thinking that takes into account unstated logical connections between things discussed in the arguments and things mentioned in the answer choices.