Stats Question (68-95-99.7 rule)

Question

On an exam whose scores followed a normal distribution, a student's z-score was −1.

 What percentage of students scored better than he did? (Use the 68-95-99.7 Rule.)

Answer 1

z-score is the number of standard deviations away from the mean, so a z of -1 is one standard deviation below the mean.

Per the empirical rule, 84% of the data is to the right of one standard deviation below the mean.