In the formula $$\bar { X } \pm z _ { a/2 } ( \sigma / \sqrt { n } )$$ , the $\alpha$/2 refers to:
A)the probability that the confidence interval will contain the population mean.
B)the probability that the confidence interval will not contain the population mean.
C)the area in the lower tail or upper tail of the sampling distribution of the sample mean.
D)the level of confidence.

Question

Quizplus · Accepted Answer

The ?/2 refers to the area in the lower tail or upper tail of the sampling distribution of the sample mean, which is used to determine the critical value $ z_{a/2} $ for constructing the confidence interval.

In the Formula Xˉ±za/2(σ/n)\bar { X } \pm z _ { a/2 } ( \sigma / \sqrt { n } )Xˉ±za/2​(σ/n​)

In the Formula $\bar { X } \pm z _ { a/2 } ( \sigma / \sqrt { n } )$