A high-voltage power supply should have a nominal output voltage of 350 V. A sample of four units is selected each day and tested for process-control purposes. The data shown in Table Q5 give the different between and observed reading on each unit and nominal voltage times ten, that is [X = (observed voltage on unit - 350) x 10] Table Q5 Sample Number X1 X2 X3 X4 6 10 15 10 4 11 4 13 10 13 12 11 10 10 7 16 10 4 4 7. 12 10 15 16 10 13 11 12 14 16 12 13 11 13 16 16 13 15 14 13 10 12 15 11 7. 10 16 16 15 10 11 14 17 12 10 18 15 7 10 11 19 12 20 13 14 11 15 Accordingly: (a) Based on Table Q5, develop x and R control charts and revise the trial control limits (b) Calculate the process capability improvement when the second population standard value, Oo is 0.274. (c) If the specification is at 350 + 5 V, calculate the capability index for both O, and describe the case. (d) By using the value of second Oo. conclude their case when the process centre www moves from 351 to 350.