Exhibit 8-2
A random sample of 121 automobiles traveling on an interstate showed an average speed of 65 mph. From past information, it is known that the standard deviation of the population is 22 mph.
-Refer to Exhibit 8-2. If we are interested in determining an interval estimate for $\mu$ at 96.6% confidence, the Z value to use is
A)1.96
B)0.483
C)2.12
D)1.645

Question

Quizplus · Accepted Answer

To find the Z value for a 96.6% confidence interval, we need to find the Z value for a 1.7% area under the normal curve on each tail. Using a standard normal distribution table, we find that the Z value for a 1.7% area is approximately 2.12. Therefore, the Z value to use for this interval estimate is 2.12.

Exhibit 8-2 a Random Sample of 121 Automobiles Traveling on an Interstate

Exhibit 8-2
a Random Sample of 121 Automobiles Traveling on an Interstate