Dole County

Expert replies

metallicafan: Master | Next Rank: 500 Posts; Posts: 142; Joined: Sun Jun 12, 2011 7:55 amFollowed by: 3 members; Thanked: 5 times

by metallicafan » Sun Apr 01, 2012 4:10 pm

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.

OA: _A_

Source: Beat The GMAT — Critical Reasoning | Sun Apr 01, 2012 4:10 pm

killer1387: Legendary Member; Posts: 581; Joined: Sun Apr 03, 2011 7:53 amFollowed by: 5 members; Thanked: 52 times

by killer1387 » Sun Apr 01, 2012 5:08 pm

A goes the best

Bill@VeritasPrep: GMAT Instructor; Posts: 1248; Joined: Thu Mar 29, 2012 2:57 pmFollowed by: 192 members; Location: Everywhere; Thanked: 503 times; GMAT Score:780

by Bill@VeritasPrep » Sun Apr 01, 2012 8:13 pm

Premise: 80% of severe front-seat injuries were not wearing seatbelts at the time of the accidents.
Conclusion: Wearing seat belts greatly reduces the risk of severe front-seat injuries.

A. If more than 20% were wearing seatbelts, then they had fewer severe injuries than you would expect based on population. Let's use 30% as a figure to see what I mean:

30% seatbelts = 20% injuries
70% no seatbelts = 80% injuries

We can see that seatbelt use leads to a smaller percentage of severe injuries than would be otherwise expected.

B. We only care about seatbelt use at the time of the accident.

C. Rear-seat passengers are irrelevant.

D. We only care about accidents that resulted in severe injuries.

E. As in D, accidents without serious injuries are not part of the argument.

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tanviet: Legendary Member; Posts: 1404; Joined: Tue May 20, 2008 6:55 pmFollowed by: 2 members; Thanked: 18 times

by tanviet » Mon Apr 02, 2012 5:54 am

This is hardest question and I do not think it is from gmatprep or og books

I meet this question many times and each time I can not do it.

the following is the only way we can understand this question.

make a tale

LAP SEATBELT KHONG LAP SEATBELT
SEVERE 2 8 10

NOT SEVERE >20

tanviet: Legendary Member; Posts: 1404; Joined: Tue May 20, 2008 6:55 pmFollowed by: 2 members; Thanked: 18 times

by tanviet » Mon Apr 02, 2012 6:02 am

SORY, I post again.

make a table like this

SEATBELT NO SEATBELT

SEVERE 2 8 10 (total severely injured)
NOT SEVERE
>20 (total seatbelt) 100 (total)

supose there are total 100, and 10 of them are severely injured.

above table is the only way which make you understand the problem

This question is similar to a math question but much harder. I never think gmat will offer this hard question. experts, members, pls, comment.

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