a good use of z-scores is to compare values in two different distributions. suppose your instructor will drop the low test when computing final grades, but he curves grades on each test. you had a 92 on the first test, and an 85 on the second. the first test had a mean of 83 and standard deviation of 6. the second test had a mean of 75 and a standard deviation of 3. the z-score for your first test is 1.5 and the z-score for the second test is 3.33 because (85 - 75)/ fulfills the formula to find the z-score.