GMAT考题：OG2017Q-DS-240

GMAT考题

Last year, if Elena spent a total of $720 on newspapers, magazines, and books, what amount did she spend on newspapers?

(1) Last year, the amount that Elena spent on magazines was 80 percent of the amount that she spent on books.

(2) Last year, the amount that Elena spent on newspapers was 60 percent of the total amount that she spent on magazines and books.

Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

EACH statement ALONE is sufficient.

Statements (1) and (2) TOGETHER are NOT sufficient.

毕出

题目分析：

设花费在报纸、杂志和书籍上的钱分别为x、y、z，有x+y+z=720题目求x的值。

（1）给出花在杂志上的钱是花在书籍上钱的80%，即y=0.8z，无法解得x的值。

（2）给出花在报纸上的钱是花在杂志和书籍钱的60%，即x=0.6(y+z)。因为y+z=720-x，代入条件2的式子得x=0.6(720-x)，解得x=270美元。题目得解。

因此，本题答案为（B），仅条件2可以解题，条件1不行。

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