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标题: 天山4－2 [打印本页]

作者: sunjueliang 时间: 2005-10-8 06:39 标题: 天山4－2

Q2:
A certain characteristic in a large population has a distribution that is symmetric about the
mean m. If 68 percent of the distribution lies within one standard deviation d of the mean,
what percent of the distribution is less than m + d ?
A. 16%
B. 32%
C. 48%
D. 84%
E. 92%

作者: himba 时间: 2005-10-8 13:23

题目说集合中都关于m点对称

然后说大于m-d小于m+d的为68％，那么两边小于m-d和大于m+d的应该分别是16％

所以小于m＋d的应该是大于m-d小于m+d的部分加上小于m-d＝84％

作者: sunjueliang 时间: 2005-10-8 19:15

谢谢，太感谢了！！！

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