Activity- statistics problems

Problem 1

If n =10, = 12 and = 1530 find coefficient of variation

Solution

${\frac {\sum x}{n}}={\bar {x}}$

$\sum {x}={{\bar {x}}\times {n}}$

$\sum {x}={12\times {10}}$

$\sum {x}=120$
σ=Failed to parse (syntax error): {\displaystyle \sqrt{ \frac{\sum {x}^{2} }{n}} -\frac{( {\sum {x}{n} ) ^{2}} }}