## Elementary Statistics (12th Edition)

The mean can be counted by summing all the data and dividing it by the number of data: $\frac{6+4+2+7+2+12}{6}=5.5$. The sorted data: 2,2,4,6,7,12. The median is the average of the 1 or 2 (here 2) middle data: (4+6)/2=5. Standard deviation=$\sqrt{\frac{\sum (x-\mu)^2}{n-1}}=\sqrt{\frac{(6-5.5)^2+(4-5.5)^2+(2-5.5)^2+(7-5.5)^2+(2-5.5)^2+(12-5.5)^2+}{5}}=3.8.$