OG11逻辑第3题

flyfairy019

3. “Life expectancy” is the average age at death of the entire live-born population.
In the middle of the nineteenth century, life expectancy in North America was 40
years, whereas now it is nearly 80 years. Thus, in those days, people must have
been considered old at an age that we now consider the prime of life.
Which of the following, if true, undermines the argument above?


(A) In the middle of the nineteenth century, the population of North America was
significantly smaller than it is today.


(B) Most of the gains in life expectancy in the last 150 years have come from
reductions in the number of infants who die in their first year of life.


(C) Many of the people who live to an advanced age today do so only because of
medical technology that was unknown in the nineteenth century.


(D) The proportion of people who die in their seventies is significantly smaller
today than is the proportion of people who die in their eighties.


(E) More people in the middle of the nineteenth century engaged regularly in
vigorous physical activity than do so today.


我的感觉是B,C都可以。答案是B。
为什么不选C呢？求教！书上的解释只有一句，说C supports the argument.

handapink

The passage states that because "In the middle of the nineteenth century, life expectancy in North America was 40 years" so => "Thus, in those days, people must have been considered old at an age that we now consider the prime of life." The conclusion can be true if people in North America in nineteenth century usually died around 40( life expectancy at that time).

B. undermines the conclusion by saying that the life expectany does not reflect how long people could live at that time correctly, because there is another issue we should consider -> "Most of the gains in life expectancy in the last 150 years have come from reductions in the number of infants who die in their first year of life. "

C. says that people can live longer today only because new medical technology which did not exist in 19th. It does not mention anything about the age of poeple in 19th. It only proves that 1. people live longer today, and 2. there was no such medical technology in back days. Therefore, it has nothing to do with the argument, or you can say it supports the argument a little bit by pointing out there was no advance medical technology in 19th, which might cause people died early.

winny0821

Two group of people were born at the same time. In the first group, five infants died at age of 1. The other 5 died at the age of 79. The average age at death for the group is 40 years old.
In the second group, all ten people died at the age of 80. The average age at death is 80. In group one, what age do you consider is an old age? 79. Not 40.

C supports the argument in that it links the increase in life expectancy to the LONGER years a person can live today than in 19th century. If C is true, then in 19th century, most people died at the age of 40, which is the prime time in today's standard. C is relevant to the argument.

flyfairy019

Got it, thanks!