Sprinklers are being installed to water a lawn. Each sprinkler waters in a circle. Can the lawn be watered completely by 4 installed sprinklers?

(1) The lawn is rectangular and its area is 32 square yards.

(2) Each sprinkler can completely water a circular area of lawn with a maximum radius of 2 yards.


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.

考题讲解

条件1,我们不知道喷头喷水范围的半径多大,所以不知道是否能覆盖整个的长方形区域。

条件2,只知道最大半径,不知道lawn的大小。

两个条件相加,按照最大半径算,可以覆盖整个lawn。但若不是最大半径,则不一定覆盖。因此依然不充分。答案为E。

所谓最大半径,就是条件2里给出的2 yards。所以根据条件2,我们能算出这些喷头最大的能覆盖的面积。因为这个面积超过了长方形的面积,所以在这个情况下是可以全部覆盖的。但如果比2 yards小,譬如变成0.1 yards,就不能全部覆盖了。

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GMATAdvanced-DS