A 95% confidence interval for a population mean is determined to be 100 to 120. If the confidence coefficient is reduced to .90, the interval for μ _____.
A) becomes narrower
B) becomes wider
C) does not change
D) becomes .1

Question

Quizplus · Accepted Answer

When the confidence level decreases (from 95% to 90% in this case), the confidence interval becomes narrower because a lower confidence level means we are accepting a higher level of uncertainty, thus requiring a smaller range to capture the population mean.

A 95% Confidence Interval for a Population Mean Is Determined