If one wants to develop a 90% confidence interval for the mean $\mu$ of a normal population, when the standard deviation $\sigma$ is known, the confidence level is
A) .10
B) .45
C) .90
D) 1.645

Question

Quizplus · Accepted Answer

The confidence level refers to the probability that the calculated confidence interval actually contains the population mean. A 90% confidence interval means there's a 90% chance that the interval includes the true mean, hence the correct answer is 90% or option C.

If One Wants to Develop a 90% Confidence Interval for the Mean