40, 45, 50, 55, 60, 75, 75, 90, 100, 100.
The list above shows the scores of 10 schoolchildren on a certain test. If the standard deviation of the 10 scores is 21.2, rounded to the nearest tenth, how many of the scores are more than 1 standard deviation below the mean of the 10 scores?  Choose the correct choice from the following choices:
A) 1
B) 2
C) 3
D) 4
E) 5
The average of {40, 45, 50, 55, 60, 75, 75, 90, 100, 100} is 69.   1 standard deviation below the mean is 69 - 21.2 = 47.8. Hence there are two scores (40 and 45) more than 1 standard deviation below the mean.   Answer 2.
<result>B</result>
40, 45, 50, 55, 60, 75, 75, 90, 100, 100.
The list above shows the scores of 10 schoolchildren on a certain test. If the standard deviation of the 10 scores is 21.2, rounded to the nearest tenth, how many of the scores are more than 1 standard deviation below the mean of the 10 scores?