Plastic sheets produced by a machine are periodically monitored for possible fluctuations in

thickness. If the true variance in thickness exceeds 2.25 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 following results (in millimeters):

226 226 232 227 225 228 225 228 229 230

Based on this sample, is there any cause for concern? Use 5% level of significance.