9.6 , 9.8 , 9.9 , 9.9 , 10.0 , 10.1 , 10.2 , 10.5
The mean and the standard deviation of the 8 numbers shown above is 10 and 0.255 respectively. What percent of the 8 numbers are within 1 standard deviation of the mean? Choices
A) 90%	B) 75%	C) 80%	D) 85%	E) 70%
Within 1 standard deviation of the mean- means in the range {mean-1*sd; mean+1*sd} = {10-1*0.255; 10+0.255} = {9.745; 10.255}.   From the 8 listed numbers, 6 are within this range so 6/8=75%.   Answer: 75%.
<result>B</result>
9.6 , 9.8 , 9.9 , 9.9 , 10.0 , 10.1 , 10.2 , 10.5
The mean and the standard deviation of the 8 numbers shown above is 10 and 0.255 respectively. What percent of the 8 numbers are within 1 standard deviation of the mean?