In a situation where the population standard deviation is known and we wish to estimate the population mean with 90 percent confidence, what is the appropriate critical value to use?
A) z = 1.96
B) z = 2.33
C) z = 1.645
D) Can't be determined without knowing the degrees of freedom.

Question

Quizplus · Accepted Answer

When the population standard deviation is known and we wish to estimate the population mean, the z-distribution is used. For a 90% confidence interval, the critical value is z = 1.645. This value corresponds to the point in the standard normal distribution where 5% of the distribution lies in each tail (totaling 10% in both tails), leaving 90% in the center.

In a Situation Where the Population Standard Deviation Is Known