Exhibit 8-3
a Random Sample of 81 Automobiles Traveling on a Section

Multiple Choice

Exhibit 8-3
A random sample of 81 automobiles traveling on a section of an interstate showed an average speed of 60 mph. The distribution of speeds of all cars on this section of highway is normally distributed, with a standard deviation of 13.5 mph.
-Refer to Exhibit 8-3. The 86.9% confidence interval for $\mu$ is

A) 46.500 to 73.500
B) 57.735 to 62.265
C) 59.131 to 60.869
D) 50 to 70