Plastic sheets produced by a machine are periodically monitored for possible fluctuations in thickness. If the true variance exceeds 1.20 square millimeters, there is cause for concern about product quality. Thickness measurements for a random sample of 10 sheets produced in a particular shift were taken, giving the results shown below (in millimeters). 230 229 227 227 230 227 a. Find the sample variance. 225 226 229 230 b. Test, at the 1% significance level, the null hypothesis that the population variance is at most 1.20 square millimeters. Click the icon to view the upper critical values of Chi-square distribution table. A. Ho: o 1.20 H: 0 1.20 Write the decision rule for this test using the significance level a with sample variance s, hypothesized variance 62, sample size n, and critical value x)^ ^ - 1,0' X (1-1 2 2 '0' -1,1-' or xn and - 1,/2 x - 1,1 -/2 What is the form of the decision rule for this test? 2 (n-1)s A. Reject Ho if 2 Xn-1,1- 2 B. Reject Ho if 2 (n-15-11-14 2 (n 1)s (n-1)s C. Reject Ho if 2 > Xn-1,a/2 or reject Ho if 1-1,1-a/2 2 Determine the critical value or values. The critical value(s) is (are) . (Round to three decimal places as needed. Use a comma to separate answers as needed.)