On an exam whose scores followed a normal distribution, a student's z-score was −2. What percentage of students scored better than he did? (Use the 68-95-99.7 Rule.)

Answer 1

The z-score measures the number of standard deviations a score is from the mean. A z score of -2 means their score was two standard deviations below the mean. Based on the Empirical Rule all but 2.4% score below the student, or 100 - 2.4 = 97.6% score above the student.