Mean = u = 720
Standard deviation = s = 6
Data Value = x = 709
The formula to calculate the z score is:
[tex]z= \frac{x-u}{s} [/tex]
Using the values, we get:
[tex]z= \frac{709-720}{6} \\ \\
z=-1.83 [/tex]
Thus the z score for the data value will be -1.83.