If the set S consists of five consecutive positive integers, what is the sum of these five integers?

(1) The integer 11 is in S, but 10 is not in S.

(2) The sum of the even integers in S is 26.


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
题目分析:(1)    由于S由5个连续的整数构成,11在S中且10不在S中,所以序列S为{11,12,13,14,15},则这5个数的和为65。(2)    所有偶数的和为26。5个数的数列要么包含3个偶数,要么包含2个偶数。如果包含3个偶数,必然首尾是偶数,中间是偶数,如果S={6,7,8,9,10},则偶数的和为24,小于26。如果S={8,9,10,11,12},则偶数的和为30,大于26,所以,S中不可能包含3个偶数,因此,S只能包含两个偶数,而包含两个相邻偶数且和为26的只能为12和14,所以,S只能为{11,12,13,14,15},则这5个数的和为65。因此,本题答案为(D),任何一个条件说明均能解题。

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