Problem
Which confidence level would produce the widest interval when estimating the mean of a population based on the mean and standard deviation of a sample of that population? A. $95 \%$ B. $90 \%$ C. $80 \%$ D. $70 \%$
Solution
Step 1 ：Calculate the Z-scores for each confidence level: 95%, 90%, 80%, and 70%
Step 2 ：Compare the Z-scores and find the highest one
Step 3 ：\(\boxed{95\%}\) produces the widest interval
