[問題] GWD18-18

[ezong]

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%


Ans: D

麻煩各位幫我解答一下 這一題...
我看不太懂題目..
謝謝!!

[Madi]

題目是問落在m+d以左的範圍內佔多少比例

若你沒學過統計學的話
在此先提個小小的觀念
不管是m-d或者m+d都算一個標準差的範圍

因此根據題意:以m為中心點左右各擴展d所夾的範圍為68%
將其二等份,則m-d和m+d各佔34%

再回到題目要問的m+d以左的範圍
就等於50%(整個左半部)+34%(m+d)=84%

[ezong]

謝謝大大的解說...我了解了
感激不盡!!