Nonconformities in automobiles fall into three categories: serious, major, and minor.

Twenty-five samples of five automobiles are chosen, and the total number of nonconformities in each category is reported. Table 8-33 shows the results. Assuming a weighting system of 50, 10, and 1 for serious, major, and minor nonconformities, respectively, construct a demerits per unit control chart. Revise the control limits if necessary, assuming special causes for points that are out of control.