作者filley (我要改變...)
看板GMAT
標題[計量] PP標準差題目
時間Thu Nov 27 16:31:19 2008
106. 11122-!-item-!-187;#058&007588
If a certain sample of data has a mean of 20.0 and a standard deviation of
3.0, which of the following values is more than
2.5 standard deviations from the mean?
(A) 12.0
(B) 13.5
(C) 17.0
(D) 23.5
(E) 26.5
答案是A
這種題目要怎麼解呢??
該不會要代標準差公式吧XD
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