4. \( (10\%) \) \( X{1}, X{2}, \ldots, X{n} \) are the independent and identically distributed random variables and follow the distribution with mean \( \mu \) and variance \( \sigma^2 \). Let \( \bar{X} = \sum{i=0}^{n} X_i / n \). Please show that \( \bar{X} \) is a consistency estimator of \( \mu \).