A recent survey of all auto accident victims in Dole County found that, of the severely injured drivers and front-seat passengers, 80 percent were not wearing seat belts at the time of their accidents. This indicates that, by wearing seat belts, drivers and front-seat passengers can greatly reduce their risk of being severely injured if they are in an auto accident.

The conclusion above is not properly drawn unless which of the following is true?

(A) Of all the drivers and front-seat passengers in the survey, more than 20 percent were wearing seat belts at the time of their accidents.
(B) Considerably more than 20 percent of drivers and front-seat passengers in Dole County always wear seat belts when traveling by car.
(C) More drivers and front-seat passengers in the survey than rear-seat passengers were very severely injured.
(D) More than half of the drivers and front-seat passengers in the survey were not wearing seat belts at the time of their accidents.
(E) Most of the auto accidents reported to police in Dole County do not involve any serious injury.

i think ans is C which states
c)More drivers and front-seat passengers in the survey than rear-seat passengers were very severely injured.

What if the majority of the people injured are sitting in the rear seat . making seat belts mandatory for front seat passengers wont help them .

D ) is explicitly mentioned in the statement, so it doesnt add any further support to the argument.

A) Of all the drivers and front-seat passengers in the survey, more than 20 percent were wearing seat belts at the time of their accidents.
-- OOS
(B) Considerably more than 20 percent of drivers and front-seat passengers in Dole County always wear seat belts when traveling by car.
-- OOS
(C) More drivers and front-seat passengers in the survey than rear-seat passengers were very severely injured.
-- Right answer choice
(D) More than half of the drivers and front-seat passengers in the survey were not wearing seat belts at the time of their accidents.
-- True, but doesn't add any support to the statement to draw conclusion.
(E) Most of the auto accidents reported to police in Dole County do not involve any serious injury.
-- OOS

Assumption Q based on connect the premise and conclusion or fill the logical gap.

A recent survey of all auto accident victims in Dole County found that, of the severely injured drivers and front-seat passengers, 80 percent were not wearing seat belts at the time of their accidents. This indicates that, by wearing seat belts, drivers and front-seat passengers can greatly reduce their risk of being severely injured if they are in an auto accident.

The conclusion above is not properly drawn unless which of the following is true?

Explanation:
--------------------
(A) Of all the drivers and front-seat passengers in the survey, more than 20 percent were wearing seat belts at the time of their accidents. ---> We know from the excerpt that
Drivers + Front-Seat Passengers = Severely Injured (20% Wearing Seat-Belts + 80% Not Wearing Seat-Belts) + Not Severely Injured (No Information)

Now, what if more than 80% of the drivers and front-seat passengers who were NOT severely injured were NOT wearing seat-belts? Using this scenario, we can say that wearing seat-belts will NOT reduce the risk of being severely injured. So the conclusion cannot be properly drawn.

Since we have to show that author's conclusion was properly drawn, we have to show that the scenario I cited above was not possible. To make the above scenario impossible, we can say that more than 80% (actually it should be 100% otherwise these people will come under the category of ‘severely injured’ ones) of the drivers and front-seat passengers who were NOT severely injured were wearing seat-belts. Also, excerpt mentions that 20% people from the severely injured category were wearing seat-belts.

So, if we add people (who were wearing seat-belts) from both the categories (severely injured & not severely injured), we'll arrive at the assumption stated in this option.

(B) Considerably more than 20 percent of drivers and front-seat passengers in Dole County always wear seat belts when traveling by car. ---> Mentions about car. Irrelevant.

(C) More drivers and front-seat passengers in the survey than rear-seat passengers were very severely injured. ---> Will not help us in any way to prove that the conclusion was properly drawn.

(D) More than half of the drivers and front-seat passengers in the survey were not wearing seat belts at the time of their accidents. ---> This cannot be the assumption in order to arrive at the author’s conclusion.

(E) Most of the auto accidents reported to police in Dole County do not involve any serious injury. ---> Irrelevant.
--------------------

Hope that helps.


Regards,
Technext
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A is correct.
Lets say there were 100 cases of "serious" accident. Then 80 of those cases were not wearing seat-belts according to the author. But 20 were. So the author assumes that wearing seat-belts can prevent serious accidents. How can that be? There are 20 cases of serious accident that were wearing seat belts! Then how can the author claim that seat-belts can prevent serious accidents? The only way this can happen is if more than 20 people in the auto-accident survey were wearing seat belts and were not seriously hurt. Choice A provides us with that number- it says more than 20% of ALL accident cases were wearing seat-belts at the time of the accident. Now 20% of ALL cases has to be > 20% of serious cases since "serious cases" is a sub-group of all cases.
Hence answer A.

Guys don't you think B can also be correct
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The proof of understanding is the ability to explain it.

i go with D too...for the same reasons mentioned by folks above....

because prose says 80% of them who had not worn seat belts were severly injured...so more than 50% were not wearing the set belts support it... isnt it?
_________________

Regards,
Harsha

Note: Give me kudos if my approach is right , else help me understand where i am missing.. I want to bell the GMAT Cat

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