The speeds of the fastballs thrown by major league baseball pitchers were measured by radar gun. The mean speed was 86 miles per hour. The standard deviation of the speeds was 5 mph. Which of the following speeds would be classified as an outlier?
A) 81 mph
B) 94 mph
C) 76 mph
D) 102 mph

Question

Quizplus · Accepted Answer

An outlier is typically defined as a value that is more than 2 standard deviations away from the mean. Here, the mean is 86 mph and the standard deviation is 5 mph. Two standard deviations from the mean would be 86 ± 10 (76 to 96 mph). The speed of 102 mph is more than 2 standard deviations above the mean, classifying it as an outlier.

The Speeds of the Fastballs Thrown by Major League Baseball