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On a standardized exam, the scores are normally distributed with a mean of 165 and astandard deviation of 40. Find the z-score of a person who scored 145 on the exam.

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The Z-score is calculated by the formula below


\begin{gathered} z-score=((x-\mu))/(\sigma)_{} \\ \mu=\operatorname{mean} \\ \sigma=s\tan dard\text{ deviation} \\ x=\text{score} \end{gathered}

Step 2: Substitute the given parameters in the formula


\begin{gathered} z-\text{score}=(145-165)/(40) \\ Z=-(20)/(40) \\ Z=-(1)/(2) \\ Z=-0.5 \end{gathered}

Hence, the z-score of a person who scored 145 on the exam is -0.5

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