The formula to find the z score in a normally distributed set of data is:
z = (x - ÎĽ) / Ď
With ÎĽ being the mean, Ď being the standard deviation, and x being the score.
Substituting these values into the formula gives us
z = (800 - 500) / 100 = 3
The z-score of the 800 point score is 3.