z-score = 0.256
Explanation:The mean score, μ = 84.28
The standard deviation, σ = 6.71
The score, X = 86
The z-score is calculated using the formula:
[tex]\begin{gathered} z-\text{score = }\frac{X-\mu}{\sigma} \\ z-\text{score = }\frac{86-84.28}{6.71} \\ z-\text{score = }\frac{1.72}{6.71} \\ z-\text{score = }0.256 \end{gathered}[/tex]Therefore, your friend's z-score = 0.256
