问一题8月JJ数学题

Jennywang2 · 发表于 2012-8-21 22:03:56

大概是说mean为86的一堆数里有百分之68的数标准方差是1，总的标准方差却是6，问92大约排在这堆数百分之多少的位置。

wtalan918 · 发表于 2012-8-25 10:20:23

112. Acertain 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%
(0 48%
(D) 84%
(E) 92%

Arithmetic Statistics

Since 68% lies between m- d and m+ d, a total
of (100 - 68)% = 32% lies to the left ofm- d and
to the right of m+ d. Because the distribution is
symmetric about m, half of the 32% lies to the
rightofm +d. Therefore, 16% lies to the right of
m+ d, and hence (100 - 16)% = 84% lies to the
left of m + d.

The correct answer is D.

估计是类似这种题狗主表述不清我觉得是

zhenyugood · 发表于 2012-8-25 12:33:32

一堆数据，在平均数上下一个标准差的范围内（就是m+d与m-d）的概率是68，所以在这个范围以外（0到m-d跟m+d到最大一个数）的概率就是100-68=32，所以小于m+d的概率就是32/2+68=84
这个题是高中学的正态分布吧

boby2028 · 发表于 2012-8-29 02:18:48

请问92在此题中有什么用处呢？？？求公式谢谢了

问一题8月JJ数学题

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