When finding the margin of error for the mean of a normally distributed population from a sample, what is the critical probability, assuming a confidence level of 58 percent ?

A 58% confidence level leaves 42% outside the confidence interval. Since this is split equally between the two tails, the area in one tail is 0.42 ÷ 2 = 0.21. Thus the critical probability is 0.21, choice D.

AI-written and checked against the verified answer.