Solution:
Given the z-score formula;
[tex]z=\frac{\bar{x}-\mu}{\sigma}[/tex]
And given the parameters;
[tex]\begin{gathered} \bar{x}=11.9,\mu=27.8,\sigma=5.8 \\ \\ \end{gathered}[/tex]
Thus;
[tex]\begin{gathered} z=\frac{11.9-27.8}{5.8} \\ \\ z=-\frac{15.9}{5.8} \\ \\ z=-2.74 \end{gathered}[/tex]
ANSWER:
[tex]z=-2.74[/tex]
