The quiz grades of a math class are given. 83, 76, 68, 97, 68, 80, 89, 74, 75, 81, 91, 90 The grades are normally distributed with a mean of 81 and a standard deviation of 9.3. What is the z-score of the highest grade in the quiz?
A) −1.72
B) −1.08
C) 1.08
D) 1.72