Each of the five divisions of a certain company sent representatives to a conference. If the numbers of representatives sent by

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问题 Each of the five divisions of a certain company sent representatives to a conference. If the numbers of representatives sent by four of the divisions were 3, 4, 5, and 5, was the range of the numbers of representatives sent by the five divisions greater than 2?
(1) The median of the numbers of representatives sent by the five divisions was greater than the average (arithmetic mean) of these numbers.
(2) The median of the numbers of representatives sent by the five divisions was 4.

选项 A、Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B、Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C、BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D、EACH statement ALONE is sufficient.
E、Statements (1) and (2) TOGETHER are NOT sufficient.

答案C

解析 Let x be the unspecified number of representatives. By considering individual positive integer values of x, the median of the numbers is found to be 4 when x = 1,2, 3, or 4, and the median of the numbers is found to be 5 when x ≥ 5. For example, the case in which x = 2 is shown below.
2,3,4,5,5
(1)    In terms of x, the average of the numbers is . If x = 1, then by  the remarks above the median is 4, which is greater than(i.e., the median is greater than the average), and the range is 5-1 = 4. If x = 5, then by the remarks above the median is 5, which is greater than (i.e., the median is greater than the average), and the range is 5 - 3 = 2; NOT sufficient.
(2)    Given the assumption that the median of the numbers is 4, it follows from the previous remarks that x can be any one of the numbers 1,2,3, and 4. If x = 1, then the range is 5 - 1 = 4, which is greater than 2. If x = 4, then the range is 5 - 3 = 2, which is not greater than 2; NOT sufficient.
Given (1) and (2), then from the previous remarks and (2) it follows that x must be among the numbers 1,2,3, and 4. From (2) it follows that 4 >, or x < 3, and thus x is further restricted to be among the numbers 1 and 2. However, for each of these possibilities the range is greater than 2: If x = 1, then the range is 5 - 1 = 4 > 2; and if x = 2, then the range is 5-2 = 3 > 2.
The correct answer is C;
both statements together are sufficient.
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本试题收录于: GMAT QUANTITATIVE题库GMAT分类
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