Question 1116934
The z-score gives a standardized value of where the individual's score was among all the others.  
If the mean were 68 and the individual got a 75, that is above the mean.  But if the z-score were .25, that would suggest the individual is slightly above the mean.  If the z-score were 2, that would suggest the individual was in the top 5% of the class.
The top 25% of individuals is a z-score of about +0.67.  With this information, one can look at the score in light of the variability in the exam, and z-scores of -1,-2,1,2 are very easy to understand in forming percentiles.