%%visits: 3 ## intuition A series of probability_density_functions eventually becomes a normal probability_density_function. ## rigour
Let X1, X2, … be independent and identically distributed random_variables with 𝔼(xi) = μ and var(Xi) = σ2 < ∞
$$ Z_n `:=` \frac{\sum _{k=1}^{n} X_k - n\mu}{\sigma \sqrt{n}} = \frac{\overline{X} - n \mu}{\frac{\sigma}{\sqrt{n} }} $$ ## exam clinic ## examples and non-examples ## resources tags :math: