We will have the following:
First, we will have that the apparent mean is:
[tex]\begin{gathered} x=\frac{8+11+17+17+7+19}{6}\Rightarrow x=\frac{79}{6} \\ \\ \Rightarrow x\approx13.2 \end{gathered}[/tex]Now, we calculate the standard deviation:
[tex]\begin{gathered} s=\sqrt{\frac{1}{N-1}\sum_{i=1}(x_i-x)^2} \\ \\ \Rightarrow s=\sqrt{\frac{1}{6-1}\sum(x_i-\frac{79}{6})^2}\Rightarrow s\approx5.2 \end{gathered}[/tex]So, the standard deviation is approximately 5.2.
