The standard Z-score is given by the equation:
[tex]\begin{gathered} Z=\frac{x-\mu}{\sigma} \\ \text{where '}\mu^{\prime}\text{ represents the mean} \\ \text{'}\sigma^{\prime}\text{ represents the standard variation} \\ ^{\prime}x^{\prime}\text{ represent the observed value} \end{gathered}[/tex][tex]\begin{gathered} Z=\frac{105-75}{10} \\ Z=\frac{30}{10} \\ Z=3 \end{gathered}[/tex]
Hence, the Z-score is 3
