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"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.

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  • dorisL

    注意 average 很有可能 跟 加权平均 有关

    解题目标是: 要证明 在90年代 年龄有40岁的,不一定被认为是老的

    过去平均年龄40, 是因为 一出生就死了的婴儿人数多占比大,拉低了整体平均年龄;现在平均年龄80,是因为婴儿死亡率降低了。暗示 可能 过去 和 现在年龄达到80岁的人数差不多,所以40岁的人在过去不一定就是老人

科目:CR逻辑

来源:OG

正确率:88.89%

难度:650-700

考点:削弱