I will choose A.

The argument is the following:

Evidence:of the severely injured drivers and front-seat passengers, 80 percent were not wearing seat belts at the time of their accidents.

Conclusion: 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

B, C and E are out of scope. D is not un assumption. Imagine all the drivers and fp were not wearing seat belts, can you draw any conclusion about wearing seat belts?.
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hey ya......

[quote="rianah100"]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.[/quote]
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I could be way off here. Please explain where I went wrong.
A- seems to be right but is also wrong-the stem just says that 80% of the injured were not belted. this means that 20% of the severely injured were belted. This does NOT mean that 20%+ of ALL drivers and front seaters were belted.
For e.g 200 were surveyed. lets say 100 were severely injured. The stem says 80 were not belted. 20 were belted. If the non-severe 100 were ALL not belted then we have LESS than 20%(20 of 200 is 10%) wearing seat belts. A cannot hold true. Only if more than 20 of the non-severely injured wore belts then A would be true

Can anyone explain?

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.

Ans is C
A) If 80% r not wearing, then doesnt it means that 20% are wearing.So looks wrong
b)Again its the same stuff
c)Looks reasonable

Should be A.

I've seen this question before and never really understood the answer until now. It is asking us to compare the probability of severe injury when an accident occurs for non-seatbelt wearers vs. seatbelt wearers.

Assume 100 accidents, now assume 10% of all accident victimsare wearing their seatbelt. So we have 10 seatbelt wearers and 90 non-seatbelt wearers. Now assume that we have 5 severe injuries which means that we have 4 (80%) non-seatbelt wearers who got serverly injured and 1 seatbelt wearer who got severely injured.

This means that 4 out of 90 non-seatbelters were severely injured = 4.44% and 1 out of 10 seatbelters were severely injured = 10%. This says that not wearing a seatbelt is the way to go.

This of course hits a breakpoint when we get to 20% of all accident victims are wearing their seatbelt. Now we have 4 out of 80 for non-seat belt vs. 1 out of 20 for seat belt, so for any higher percentage of seatbelt use for all accident victimsthe statistics will favor seatbelt use as a means to reduce the likelihood of serious injury when involved in an accident.