A manufacturer of candy must monitor the temperature at which the candies are baked. Too much variation will cause inconsistency in the taste of the candy. Past records show that the standard deviation of the temperature has been 1.2oF. A random sample of 30 batches of candy is selected, and the sample standard deviation of the temperature is 2.1oF.
a. At the 0.05 level of significance, is there evidence that the population standard deviation has increased above 1.2oF?
b. What assumption do you need to make in order to perform this test?
c. Compute the p-value in (a) and interpret its meaning.