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. The 96.6% confidence interval for $\mu$ is
A)63.00 to 67.00
B)60.76 to 69.24
C)61.08 to 68.92
D)60.00 to 80.00

Question

Quizplus · Accepted Answer

The 96.6% confidence interval for $\mu$ is 60.76 to 69.24. This is because the z-score for a 96.6% confidence level is 2.326, and the standard error of the mean is 22/sqrt(121) = 2.08. Therefore, the confidence interval is 65 +/- 2.326 * 2.08 = 60.76 to 69.24.

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