1 Question

jjjjjj

A recent survey of all auto accident victims in Dole county found that, if 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-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?
1 .Of all the drivers and front-seat passengers in the survey more than 20 percent were wearing seat bells at the time fo their accidents.
2. considerably more than 20 percent of drivers and front-passengers in Dole county always wear seat belts when traveling by car.
3. More than half of the drivers and front-passengers in the survey were not wearing the seat belts at the time of their accidents.

请解释为什么1 是正确答案. THX

jjjjjj

Got you! Thanks!
Geee, do I have time to deal with this crap in this way during the real test? Quite doubt it.

猫猫头

这道题其实有点像数学我觉得
它说在所有受伤者中，有大于２０％的人系了安全带，那就说明有少于８０％的人是没有系安全带受伤的
但是题干中说在严重受伤者中，有８０％的人没系安全带受了重伤
这就说明，不系安全带受重伤的比率比较大
不知道我说明白了吗？