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The larger the z score is, negative or positive, tells you how unusual it is.\\  \subsection{Calculating percentiles and probabilities with normal models}  z scores can tell us $how$ unusual an observation is. This means that we start using z tables here.\\  $\textbf{Example} $\textbf{Example}$  ACT scores are distributed normally with mean 21 and standard deviation 5. If Adam got a 27 on his ACT, what is his percentile score?\\  calculate z score. $z=\frac{27-21}{5}=1.2. Looking up on a standard normal table, percentile is 0.8849.\\  so adam score is in the 88.49th percentile.\\