## Elementary Statistics (12th Edition)

$H_{0}:\sigma_1=sigma_2,$ $H_{a}:\sigma_1\ne \sigma_2$. :$F=\frac{s_1^2}{s_2^2}=\frac{18.6028^2}{8.9604^2}=4.31.$ The critical values by the table with df=min(23,13)=13: $f_{0.025}$ is between 2.4665 and 2.5699. If the value of the test statistic is in the rejection region, we reject the null hypothesis. 2.5699 is less than 4.31, hence we reject the null hypothesis.