A simple random sample of 28 filtered 100-mm cigarettes is obtained from a normally distributed population, and the tar content of each cigarette is measured. The sample has a standard deviation of 0.18 mg. Use a 0.01 significance level to test the claim that the tar content of filtered 100-mm cigarettes has a standard deviation different from 0.25 mg, which is the standard deviation for unfiltered king-size cigarettes. Complete parts (a) through (d) below.