Mean:-
[tex]\\ \tt\hookrightarrow \dfrac{\sum x}{n}=\dfrac{210}{10}=21[/tex]
Standard Deviation:-
[tex]\\ \tt\hookrightarrow \sqrt{\dfrac{\sum x^2}{n}-(\sum x/n)^2}[/tex]
[tex]\\ \tt\hookrightarrow \sqrt{\dfrac{5006}{10}-(21)^2}[/tex]
[tex]\\ \tt\hookrightarrow \sqrt{500.6-441}[/tex]
[tex]\\ \tt\hookrightarrow \sqrt{59.6}[/tex]
[tex]\\ \tt\hookrightarrow 7.72[/tex]
Variance:-
[tex]\\ \tt\hookrightarrow (S. D)^2=(7.72)^2=59.6[/tex]