问题 单项选择题

Company R’s annual profit has increased by a constant amount each calendar year since 1985. What was Company R’s annual profit in 1991 ?()
(1)In 1985 Company R’s annual profit was $212.000; in 1989 Company R’s annual profit was $242,000.
(2)Company R’s annual profit has increased by $7,500 each year since 1985.

A.条件(1)充分,但条件(2)不充分.

B.条件(2)充分,但条件(1)不充分.

C.条件(1)和(2)单独都不充分,但条件(1)和条件(2)联合起来充分.

D.条件(1)充分,条件(2)也充分.

E.条件(1)和条件(2)单独都不充分,条件(1)和条件(2)联合起来也不充分.

答案

参考答案:A

解析:

由(1)可得公司X的年利润从1985年到1989年增长了242,000-212,000=30,000美元,所以平均每年增长7,500美元,因此到1991年该公司的年利润为242,000+7,500×2=257,000美元,所以(1)充分;因为(2)中不知道1985年的年利润是多少,因此无法求出1991年的年利润是多少,所以(2)不充分。

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