Solution:-
Let us take \[10\] multiples of \[3\] are \[3,6,9,12,15,18,21,24,27,30\]
We know that Mean = \[\bar{X}=\sum\limits_{i=1}^{a}{{{x}_{i}}}\]
\[\overline{x}=(3+6+9+12+15+18+21+24+27+30)/10\]
= \[165/10\]
= \[16.5\]
Draw the table of the data and append other columns after calculations.
Then, Variance
\[{{\sigma }^{2}}=\frac{1}{n}\sum\limits_{i=1}^{a}{{{({{x}_{i}}-\overline{x})}^{2}}}\]
=\[(1/10)\times 742.5\]
= \[74.25\]
Therefore, Mean = \[16.5\] and Variance = \[74.25\]