We want to get the standard deviation of the distribution;
From which we can compute;
[tex]SD=\sqrt[]{\frac{\sum ^{}_{}f(x-\operatorname{mean})^2}{\sum ^{}_{}f}}[/tex]
When we input the values, we have
[tex]SD=\sqrt[]{\frac{250.5002}{18}}=\sqrt[]{11.1384}=3.3375[/tex]
