Question

How to use the results of part (b) and appropriate computation formulas to compute the sample variances s2 and sample standard deviation s.

Answer 1

$s^2=\displaystyle\sum\frac{(x-\bar x)^2}{n-1}=\frac1{n-1}\sum(x^2-2x\bar x+{\bar x}^2)=\frac{\displaystyle\sum x^2-2\bar x\sum x+{\bar x}^2}{n-1}$

where $\bar x=22$ is the mean. Since

$\sum x^2=2568$
$\sum x=110$

you have variance

$s^2=\dfrac{2568-2(22)(110)+22^2}{5-1}=37$

and so the standard deiviation is

$s=\sqrt{37}\approx6.083$