2 A summary of 40 values of \(x\) gives the following information:
$$\Sigma ( x - k ) = 520 , \quad \Sigma ( x - k ) ^ { 2 } = 9640$$
where \(k\) is a constant.
- Given that the mean of these 40 values of \(x\) is 34 , find the value of \(k\).
- Find the variance of these 40 values of \(x\).