A machine manufactures metal balls which are classified (according to their diameter) in three categories: A, B and C. A log is said to be of category A if its diameter is less than 9.5 mm, of category B if its diameter is at least 9.5 mm and not more than 10.5 mm, and of category C if its diameter is greater than 10.5 mm. Previous studies have shown that 80% of the logs coming from the machine were of category A and that there were three times more Category B logs than Category C. A special random sample of 200 logs is taken from the production of the machine, and there are 156 of category A, 32 of category B and 12 of category C. We wish to verify the hypothesis that the distribution of the balls according to the three categories have not changed since the last study. Give the observed value x of the appropriate test, as well as the critical point Co at the threshold of a = 5% . Choose between the answers A B C D E F G H 12 = 3.633 x2 = 3.633 x2 = 2.633 x2 = 2.633 x2 = 1.6332 = 1.633 2 = 0.6332 = 0.633 Ca = 5.991 Ca = 6.991 Ca = 5.991 Ca = 6.991 Ca - 5.991 Ca = 6.991 Ca = 5.991 Ca = 6.991