A 90% confidence interval estimate for a population mean is determined to be 72.8 to 79.6. If the confidence level is reduced to 80%, the confidence interval for becomes narrower.

Question

A 90% confidence interval estimate for a population mean  is determined to be 72.8 to 79.6. If the confidence level is reduced to 80%, the confidence interval for  becomes narrower.

Quizplus · Accepted Answer

When the confidence level is reduced, the interval becomes narrower because the level of certainty needed to obtain a wider interval is lower. Therefore, it is true that the confidence interval for the population mean will become narrower at an 80% confidence level than at a 90% confidence level.

A 90% Confidence Interval Estimate for a Population Mean