Answer
Range = $5$
Sample variance = $s^{2}=3.7$
Sample standard deviation = $s =1.924$
Work Step by Step
Recall the shortcut formula for calculating the variance ($s^{2}$)$:$
$$s^{2}=\frac{\sum x_{i}^{2}-\frac{(\sum x_{i})^{2}}{n}}{n-1}$$
Let's create a table in which we compute $\displaystyle \sum x_{i}$ and $\displaystyle \sum x_{i}^{2}$:
$$ \begin{array}{rrr}
& x & x^{2}\\
\hline & 39 & 1521\\
& 42 & 1764\\
& 40 & 1600\\
& 37 & 1369\\
& 41 & 1681\\\hline
\rm Sum & 199 & 7935
\end{array}$$
Plug in the given values (there are $n=5$ data items):
$$\begin{align*}
s^{2}&= \displaystyle \frac{7935-\frac{(199)^{2}}{5}}{5-1} & & \\
& =3.7 \\\\
s&= \sqrt{3.7} =1.924 \end{align*}$$
The range is the difference between the largest and smallest data item:
$42-37=5$
