The z-score formula is: $z = \frac{x - \mu}{\sigma}$
Where $x$ is the value we're interested in (30 minutes), $\mu$ is the mean (45 minutes), and $\sigma$ is the standard deviation (8 minutes).
So, $z = \frac{30 - 45}{8} = -1.875$
Now, we can use a z-table or
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