It is important that the variance of the percentage impurity levels of a chemical don't exceed 4.0. A random sample of 20 consignments had a sample variance of 5.62. a) Test the hypothesis that the population variance is greater than 4.0 at a 5% level of significance, using the rejection region (critical value) method. b) At what level of significance, you would reject the zero hypothesis that the population variance is greater than 4.0