2.68 Traffic violations A company decides to examine the number of points its employees have accumulated in the last two years on their driving record point system. A sample of twelve employees yields the following observations:

0 5 3 4 8 0 4 0 2 3 0 1

a. The standard deviation is 2.505. Find and interpret the range.

b. The quartiles are Q1 = 0, median = 2.5, Q3 = 4. Find the interquartile range.

c. Suppose the 2 was incorrectly recorded and is supposed to be 20. The standard deviation is then 5.625 but the quartiles do not change. Redo parts a and b with the correct data and describe the effect of this outlier.

Which measure of variability, the range, IQR, or standard deviation is least affected by the outlier? Why?