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

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 the sample size was 25 (other factors remain unchanged) , the interval for $\mu$ would

A) not change
B) become narrower
C) become wider
D) become zero