The formula to calculate the z-score is given by:
[tex]z=\frac{x-\mu}{\sigma}[/tex]Where
[tex]\begin{gathered} x=score \\ \mu=\operatorname{mean} \\ \sigma=s\tan dard\text{ deviation} \end{gathered}[/tex]For part A
x=33
[tex]z=\frac{33-25}{4}=2[/tex]z-score =2
For part B
x=21
[tex]z=\frac{21-25}{4}=\frac{-4}{4}=-1[/tex]z-score= -1
For Part C
x=15
[tex]z=\frac{15-25}{4}=-\frac{10}{4}=-2.5[/tex]z-score=-2.5
For part D
x=39
[tex]z=\frac{39-25}{4}=\frac{14}{4}=3.5[/tex]z-score=3.5
For part E
x=31
[tex]z=\frac{31-25}{4}=\frac{6}{4}=1.5[/tex]z-score=1.5