Answer
Sample variance = $s^{2}=3.3333$
Sample standard deviation = $s =1.826$
Work Step by Step
Recall the shortcut formula for calculating the variance ($s^{2}$)$:$
$$s^{2}=\frac{\sum_{i=1}^{n}x_{i}^{2}-\frac{\left(\sum_{i=1}^{n}x_{i}\right)^{2}}{n}}{n-1}$$
Plug in the given values:
$$\begin{align*}
s^{2}&= \displaystyle \frac{84-\frac{\left(20\right)^{2}}{10}}{10-1} & & \\
& =3.3333 \\\\
s&= \sqrt{4.8889} =1.826 \end{align*}$$
