Answer:
Z = 1.25
Step-by-step explanation:
[tex]\displaystyle Z=\frac{\text{Observed Value}-\text{Mean of the Sample}}{\text{Standard Deviation of the Sample}}\\\\Z=\frac{x-\mu}{\sigma}\\ \\Z=\frac{87-82}{4}\\ \\Z=\frac{5}{4}\\ \\Z=1.25[/tex]
Hence, Michael's z-score is 1.25, which means that he scored 1.25 standard deviations above the class average.