# Question about Statistical quality control

Small boxes of NurtraFlakes cereal are labeled œnet weight 10 ounces. Each hour, random samples of size n = 4 are weighed to check process control Five hours of observations yielded the following:

Weight

Time Box 1 Box 2 Box 3 Box 4

9 a.m. 9.8 10.4 9.9 10.3

10 a.m. 10.1 10.2 9.9 9.8

11 a.m. 9.9 10.5 10.3 10.1

Noon 9.7 9.8 10.3 10.2

1 P.M. 9.7 10.1 9.9 9.9

Using these data, construct limits for x- and R-charts. Is the process in control? What other steps should the QC department follow at this point?

I have already answered the questions. What I need help is with the Excel Solver, that’s where I am having problems. It is within control. And the QC department should increase the sample size to provide a clearer indication as to both control limits and whether or not the process is in control. And the smallest mean is 9.9 and the largest is 10.2 and the largest sample range is 0.6. I am just having problems with the Excel Solver.

The mean factor A sq 2 = 0.577 sample size 5

The upper range D 4 = 2.114 sample size 5

The lower range D 3 = 0 sample size 5

These are used in the formula to receive the UCL and LCL

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