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标题: expectancy有均值的含义吗？ [打印本页]

作者: moonlightle 时间: 2008-9-8 21:11
标题: expectancy有均值的含义吗？

2. The average life expectancy for the United States population as a whole is 73.9 years, but

children born in Hawaii will live an average of 77 years, and those born in Louisiana, 71.7

years. If a newlywed couple from Louisiana were to begin their family in Hawaii, therefore, their

children would be expected to live longer than would be the case if the family remained in

Louisiana.

Which of the following statements, if true, would most significantly strengthen the conclusion

drawn in the passage?

A. As population density increases in Hawaii, life expectancy figures for that state are likely to

be revised downward.

B. Environmental factors tending to favor longevity are abundant in Hawaii and less

numerous in Louisiana.

C. Twenty-five percent of all Louisianans who move to Hawaii live longer than 77 years.

D. Over the last decade, average life expectancy has risen at a higher rate for Louisianans

than for Hawaiians.

E. Studies show that the average life expectancy for Hawaiians who move permanently to

Louisiana is roughly equal to that of Hawaiians who remain in Hawaii.

expectancy有均值的含义吗？

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