Answer 1

25%
Standard deviation is expressed in the following manner:

\[\sigma = \sqrt{\frac{1}{n} \sum_i {x_i}^2 - \left( X \right)^2}\]

\[ = \sqrt{\frac{1530}{10} - \left( 12 \right)^2}\]

\[ = \sqrt{9}\]

\[ = 3\]

\[CV = \frac{\sigma}{X} \times 100\]
\[ = \frac{3}{12} \times 100\]
\[ = 25 %\] %