many of the inventoried textbooks were purchased by the two schools combined during the years 1974,1975,and 1976?
A.495
B.940
C.1020
D.1435
E.2800
答案：D
Shool X purchased 300 textbooks in 1971 and all of these textbooks either were counted in the inventory or had been thscarded before the inventory, what percent of these textbooks had been discarded?
A.10%
B.20%
C.50%
D.80%
E.100%
答案：C
?h of the following statements can be inferred from the graph?
(1) School X has a smaller enrollment than School Y.
(2) 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.
(3) According to the inventory, School X and School Y purchased the same number of textbooks in 1976.
B.(1) only
C.(2) only
D.(1) and (2)
E.(2) and (3)
答案：C
