Prep2一题请高人指点

legationq

9.4    9.9    9.9    9.9  10.0  10.2  10.2  10.2 10.5

The mean and the standard deviation of the 8 number are 10.0 and  0.3. What percent of the 8 numbers are within 1 standard deviation of the mean?

answer choices are    90%   80%  75%  70%

summerice14

75% , 6 numbers is in between(9.7,10.3), but why didn't you offer 9 numbers above

legationq

Thank you very much!  Sorry i made a typing mistake.