2 The data in the table opposite shows the levels of contaminant in a chemical product:

(a) Plot a histogram.

(b) Plot an individuals or run chart.

(c) Plot moving mean and moving range charts for grouped sample size n  4.

Interpret the results of these plots.

Sample Result (ppm) Sample Result (ppm)
1 404.9 41 409.6 2 402.3 42 409.6 3 402.3 43 409.7 4 403.2 44 409.9 5 406.2 45 409.9 6 406.2 46 410.8 7 402.2 47 410.8 8 401.5 48 406.1 9 401.8 49 401.3 10 402.6 50 401.3 11 402.6 51 404.5 12 414.2 52 404.5 13 416.5 53 404.9 14 418.5 54 405.3 15 422.7 55 405.3 16 422.7 56 415.0 17 404.8 57 415.0 18 401.2 58 407.3 19 404.8 59 399.5 20 412.0 60 399.5 21 412.0 61 405.4 22 405.9 62 405.4 23 404.7 63 397.9 24 403.3 64 390.4 25 400.3 65 390.4 26 400.3 66 395.5 27 400.5 67 395.5 28 400.5 68 395.5 29 400.5 69 398.5 30 402.3 70 400.0 31 404.1 71 400.2 32 404.1 72 401.5 33 403.4 73 401.5 34 403.4 74 401.3 35 402.3 75 401.2 36 401.1 76 401.3 37 401.1 77 401.9 38 406.0 78 401.9 39 406.0 79 404.4 40 406.0 80 405.7