Concerning confidence intervals, which statement is most nearly correct?
A)We should use z instead of t when n is large.
B)We use the Student's t distribution when σ is unknown.
C)We use the Student's t distribution to narrow the confidence interval.

Question

Quizplus · Accepted Answer

The statement "We use the Student's t distribution when σ is unknown" is correct. When the population standard deviation is unknown, we use the t distribution to estimate the standard error of the mean. However, when the sample size is large (typically n>30), we can use the z distribution instead of the t distribution. The statement "We use the Student's t distribution to narrow the confidence interval" is incorrect since the width of the confidence interval depends on the level of confidence, sample size, and sample standard deviation or standard error.

Concerning Confidence Intervals, Which Statement Is Most Nearly Correct