Let's begin by listing out the information given to us:
n = 500, mean = 110, sd = 10, x = 138
[tex]\begin{gathered} z=\frac{DataPoint-Mean}{StandardDeviation} \\ z=\dfrac{x-\mu}{\sigma}=\frac{138-110}{10}=\frac{28}{10}=2.8 \\ z=2.8(the\text{ }datapoint\text{ }is\text{ }above\text{ }average) \end{gathered}[/tex]