Board logo

标题: [求助]prep-ps1-118 [打印本页]

作者: lisony    时间: 2007-10-17 12:12     标题: [求助]prep-ps1-118

求助,这题highlight部分怎么理解?思路是什么?prep里这种题出了4道,一句话没明白,就影响4道题。9天就考试了,急!先谢谢了!!

118. 12240-!-item-!-187;#058&008164

For a certain examination, a score of 58 was 2 standard deviations below the mean, and a score of 98 was 3 standard deviations above the mean.  What was the mean score for the examination?

 

(A) 74

(B) 76

(C) 78

(D) 80

(E) 82


作者: lizhihuantu    时间: 2007-10-29 20:27

同问!!顶!!!


作者: shawlen    时间: 2007-12-15 10:00     标题: 平均数M,方差S,M-2S=58,M+3S=98,M=74

[em03]
作者: tony9721    时间: 2007-12-16 19:33

up,ding !!!!!




欢迎光临 国际顶尖MBA申请交流平台--TOPWAY MBA (http://forum.topway.org/) Powered by Discuz! 7.2