$\sum_{i = 1}^{n}(X_{i}-\mu)=\sigma^{2}$
$\sum_{i = 1}^{n}(X_{i}-\mu)^{2}=0$
$\sum_{i = 1}^{n}(X_{i}-\mu)^{2}=n\sigma^{2}$
$\sum_{i = 1}^{n}(X_{i}-\mu)=0$
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