Question

How confident? The figure below shows the result of taking $25$SRSs from a Normal population and constructing a confidence interval for each sample. Which confidence level—$80\%,90\%,95\%$, or $99\%$— do you think was used? Explain

Short answer

The nearest confidence level is $80\%$.

Step-by-step solution

Given Information

The result of $25$SRSs:

Explanation

The red lines under the curve represent the sample means that does not contain the true population mean $\mu$.

We note that there are $4$out of the $25$samples that do not contain the true proportion and thus $21$out of the $25$samples contain the true mean:

$\frac{21}{25}=0.84=84\%$

The nearest confidence level is $80\%$