How many of the inventoried textbooks were purchased by the two schools combined during the years 1974, 1975, and 1976? Which o

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问题 How many of the inventoried textbooks were purchased by the two schools combined during the years 1974, 1975, and 1976?
Which of the following statements can be inferred from the graph?
I  School X has a smaller enrollment than School Y.
II  If the age of a book is the number of years since purchase, then the average (arithmetic mean) age of a book in the School Y inventory is less than that of a book in the School X inventory.
III  According to the inventory, School X and School Y purchased the same number of textbooks in 1976.

选项 A、None
B、I only
C、II only
D、I and II
E、II and III

答案C

解析 下面哪一句话可以从题目的图表中推断出来? I 学校X的在册学生比学校Y的在册学生少; II若书的年龄为图书购买后的年数,那么学校Y库存图书的平均年龄比学校X库存图书的平均年龄小; III根据库存,学校X和学校Y在1976年购买的教科书的数目相同。
解:本题的正确答案是(C)。由图表中图书的库存信息无法得到学校X与学校Y的学生的多少,所以I肯定不对;II中涉及库存图书的平均年龄,学校X库存图书的平均年龄为:8×15%+7×10%+6×19%+5×23%+4×13%+3×12%+2×8%=5.23,学校Y库存图书的平均书龄为:8×0.12%+7×0.08%+6×0.13%+5×0.2%+4×0.18%+3×0.21%+2×0.08%=3.91,所以II一定正确,其实由图表也可观察到学校X的年龄比较大的图书所占的比例均大于学校Y的也可判断II是正确的;由两学校的库存总量不同,可推知III肯定不对。
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本试题收录于: GRE QUANTITATIVE题库GRE分类
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