Scores on the American College Testing (ACT) college entrance exam follow the Normal distribution with mean 18 and standard deviation 6. Wayne's standard score on the ACT was -1.1.
Wayne scored better than approximately
A) 1.1% of the people who took the exam.
B) 13.57% of the people who took the exam.
C) 11.40% of the people who took the exam.
D) 86.43% of the people who took the exam.

Question

Quizplus · Accepted Answer

A standard score (or z-score) of -1.1 indicates that Wayne's score was 1.1 standard deviations below the mean. In a normal distribution, a z-score of -1.1 corresponds to approximately the 13.57th percentile, meaning Wayne scored better than approximately 13.57% of the people who took the exam.

Scores on the American College Testing (ACT) College Entrance Exam