A company produces a service part for electric vehicles. Each unit is either labelled as defective or non-defective after a quality test is conducted. The parts arrive at the testing facility in boxes, with each box containing 20 units of the product. Suppose that the quality inspector have checked 8 boxes, with the number of defective units from those boxes given as follows. What is the UCL of the p-chart with the confidence level 99.73%