问题
单项选择题
Questions refer to the following graph.
1977～1978 TEXTB()OK INVENTORY FOR SCHOOLS X AND Y BY YEAR OF PURCHASE (as a percent of the 1977～1978 inventory)
Note：All books were purchased new on July 1 of each year.
How many of the inventoried textbooks were purchased by the two schools combined during the years 1974, 1975, and 1976
答案
参考答案：D
解析： 学校X在1974，1975，1976年购买的图书总数为：
1500×(13%+12%+8%)=495
学校Y在1974，1975，1976年购买的图书总数为：
2000×(18%+21%+8%)=940
两个学校购买图书的总数=495+940=1435