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. If we are interested in determining an interval estimate for $\mu$ at 86.9% confidence, the z value to use is

A) 1.96
B) 1.31
C) 1.51
D) 2.00