Batch pH 1 6.5 2 6.2 3 6.7 4 6.7 5 6.2 6 6.1 7 6.8 8 6.4 9 6.0 10 6.6 11 6.7 12 6.9 13 6.2 14 6.9 15 6.1 16 6.5 17 6.3 18 6.2 19 6.9 20 6.6 21 6.7 22 6.6 23 6.3 24 6.6 25 6.2 26 6.1 27 6.8 28 6.6 29 6.4 30 6.0 31 6.5 32 6.0 33 6.5 34 6.8 35 6.2 36 6.0 37 6.6 38 6.3 39 6.2 40 6.7 41 6.2 42 6.4 43 6.3 44 6.7 45 6.1 46 6.3 47 6.0 48 6.6 49 6.8 50 6.5 51 6.6 52 6.1 53 6.3 54 6.8 55 6.3 56 6.7 57 6.1 58 6.6 59 6.6 60 6.6 61 6.7 62 6.2 63 6.5 64 6.0 65 6.8 66 6.2 67 6.0 68 6.1 69 6.8 70 6.7 71 6.8 72 6.3 73 6.6 74 6.3 75 6.6 76 6.4 77 6.7 78 6.4 79 6.2 80 6.1 81 6.4 82 6.2 83 6.7 84 6.5 85 6.8 86 6.2 87 6.7 88 6.5 89 6.1 90 6.5 91 6.7 92 6.0 93 6.0 94 6.6 95 6.2 96 6.4 97 6.1 98 6.5 99 6.1 100 6.9

(15 marks) A manufacturer of a special chemical fertilizer is concerned with the pH of finished batches of product. A series of careful measurements reveals the pH values, see Minitab data PH. (a) (6 marks) Construct a control chart for the data, use zone boundaries. (b) (3 marks) is the process in control? If not, when does the our-of-control behaviour occur? (C) (6 marks) Drop the out-of-control points (assuming that you have dis- covered them) and reconstruct the control chart. In the process now in control? If not, when does the our-of-control behaviour occur