Prep-DS-126

hanxiao257

126.        12631-!-item-!-187;#058&009380
9.4  9.9  9.9  9.9  10.0  10.2  10.2  10.5
The mean and the standard deviation of the 8 numbers shown are 10.0 and 0.3, respectively.  What percent of the 8 numbers are within 1 standard deviation of the mean?

(A) 90%
(B) 85%
(C) 80%
(D) 75%
(E) 70%

hanxiao257

回复 2# pansy


    感谢感谢

pansy

1 standard deviation of the mean
表示  10-0.3<number<10+0.3
9.7＜9.9  9.9  9.9  10.0  10.2  10.2＜10.3
有六个数在之中9.7和10.3之间,  6/8=75%