Seat Belts

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gmattester: Master | Next Rank: 500 Posts; Posts: 172; Joined: Wed Oct 31, 2007 11:21 am; Thanked: 1 times

by gmattester » Thu Aug 14, 2008 6:11 am

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.

Source: Beat The GMAT — Critical Reasoning | Thu Aug 14, 2008 6:11 am

raunekk: Legendary Member; Posts: 1159; Joined: Wed Apr 16, 2008 10:35 pm; Thanked: 56 times

by raunekk » Thu Aug 14, 2008 7:25 am

imo:A

gmattester: Master | Next Rank: 500 Posts; Posts: 172; Joined: Wed Oct 31, 2007 11:21 am; Thanked: 1 times

by gmattester » Thu Aug 14, 2008 7:51 am

OA is "A". Can you plz. explain this

geoshieh: Newbie | Next Rank: 10 Posts; Posts: 3; Joined: Wed Jul 16, 2008 7:35 am

by geoshieh » Thu Aug 14, 2008 11:31 am

There are 3 scenarios here for survey pools.

1) Total Driver and Passenger (D&P) w/ seat belt = 20%
Total D&P w/o seat belt = 80%

If this was the case, and 80% of severely injured were D&Ps w/o seat belts, then this indicates that there is no greater risk of being severly injured if you didnt wear a seat belt. You have to compare ratios, which in this case is equal.

2) Total D&P w/ seat belt = 10% (less than 20%)
Total D&P w/o seat belt = 90%

In this case if they found 80% of severly injured were D&Ps w/o seat belts, then it shows that you can decrease risk of being severly injured by NOT wearing seatbelts, which weakens the conclusion.

3) Total D&P w/ seat belt = 40% (greater than 20%)
Total D&P w/o seat belt = 60%

Similarly, in this case if they found 80% of severly injured were D&Ps w/o seat belts, then it shows that you increase risk of being severly injured by NOT wearing seatbelts, which is needed to draw the conclusion.

Remember, 60% of the total pool did not wear seatbelts, and 80% of the severly injured did not wear seatbelts, so clearly you have a higher risk of being severly injured by not wearing a seatbelt.

Whereas 40% DID wear a seatbelt, and only 20% of the severly injured did wear seatbelts, so clearly you have a lower risk of being injured.

gmattester: Master | Next Rank: 500 Posts; Posts: 172; Joined: Wed Oct 31, 2007 11:21 am; Thanked: 1 times

by gmattester » Thu Aug 14, 2008 1:04 pm

geoshieh wrote:There are 3 scenarios here for survey pools.

1) Total Driver and Passenger (D&P) w/ seat belt = 20%
Total D&P w/o seat belt = 80%

If this was the case, and 80% of severely injured were D&Ps w/o seat belts, then this indicates that there is no greater risk of being severly injured if you didnt wear a seat belt. You have to compare ratios, which in this case is equal.

2) Total D&P w/ seat belt = 10% (less than 20%)
Total D&P w/o seat belt = 90%

In this case if they found 80% of severly injured were D&Ps w/o seat belts, then it shows that you can decrease risk of being severly injured by NOT wearing seatbelts, which weakens the conclusion.

3) Total D&P w/ seat belt = 40% (greater than 20%)
Total D&P w/o seat belt = 60%

Similarly, in this case if they found 80% of severly injured were D&Ps w/o seat belts, then it shows that you increase risk of being severly injured by NOT wearing seatbelts, which is needed to draw the conclusion.

Remember, 60% of the total pool did not wear seatbelts, and 80% of the severly injured did not wear seatbelts, so clearly you have a higher risk of being severly injured by not wearing a seatbelt.

Whereas 40% DID wear a seatbelt, and only 20% of the severly injured did wear seatbelts, so clearly you have a lower risk of being injured.

Thanks ........
I got it.....

kris77: Master | Next Rank: 500 Posts; Posts: 300; Joined: Sat Aug 22, 2015 10:33 am

by kris77 » Thu May 12, 2016 12:42 pm

I am leaning more towards A, but I'm not sure about it.

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