Faulty pixels. In LCD screens, every attempt is made to make sure that all pixels illuminate when they receive a signal, but it is impossible to ensure that every pixel in a large screen will actually work. A screen is determined to be defective if more than 2 pixels fail to light. Every week 500 screens are randomly selected and a quality control team member counts the number of defective screens.

Out of 500 screens, management would like an average of no more than 5 defective screens. The results for the last 50 weeks are shown in the following table.

Week Defective Screens Week Defective Screens Week Defective Screens 1 5 18 4 35 6 2 6 19 4 36 6 3 4 20 4 37 7 4 5 21 3 38 3 5 1 22 3 39 8 6 7 23 5 40 5 7 1 24 3 41 7 8 4 25 7 42 5 9 3 26 10 43 5 10 4 27 5 44 5 11 4 28 11 45 5 12 6 29 2 46 8 13 4 30 3 47 3 14 3 31 2 48 6 15 4 32 5 49 4 16 1 33 11 50 4 17 4 34 9

a) Create a c chart.

b) Is the number of defective screens out of control?
Comment.