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题库 / Prep2007E2-DS-115
List S and list T each contain 5 positive integers, and for each list the average (arithmetic mean) of the integers in the list is 40. If the integers 30, 40, and 50 are in both lists, is the standard deviation of the integers in list S greater than the standard deviation of the integers in list T ?
(1) The integer 25 is in list S.
(2) The integer 45 is in list T.
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.
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【standard deviation和mean类型题】每个集合有5个数，30,40,50在S和T都有，均值都是40，问S的标准方差和T的标准方差的大小；
1-S 里第4个数是25
2-T里第4个数是45
知道平均数了，剩的最后2个数分别可以算出来，相互比较就可以了，（1+2）可行
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