Q2 (Ref: Q. 10-5, p 352-353): In a refinery, the octane rating of gasoline produced is measured by taking one observation from each batch. Twenty observations follow. 3 sigma a) Construct Three Sigma control charts for the individual unit and moving range. Is the process in control? b) A new batch has octane rating of 94.0. Using the control charts in part a, is the process still in control? Observation Observation number Octane Rating number Octane Rating 89.2 11 85.4 86.5 12 91.6 88.4 13 87.7 91.8 14 85 90.3 15 91.5 DYS VO 87.5 16 90.3 92.6 17 85.6 87 18 90.9 89.8 19 82.1 10 92.2 20 85.8