2. 职称英语
  3. How many of the inventoried textbooks were purchased by the two schools combined

How many of the inventoried textbooks were purchased by the two schools combined

游客2024-01-12  17
问题 How many of the inventoried textbooks were purchased by the two schools combined during the years 1974, 1975, and 1976? [br] 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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