Small boxes of NutraFlakes cereal are labeled net weight 10

Small boxes of NutraFlakes cereal are labeled \"net weight 10 ounces.\" Each hour, random samples of size n=4 boxes are weighed to check process control. five hours of observations yielded the following:

Weight

Time Box1 Box2 Box3 Box4

9am 9.8 10.4 9.9 10.3

10am 10.1 10.2 9.9 9.8

11am 9.9 10.5 10.3 10.1

noon 9.7 9.8 10.3 10.2

1pm 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?

Solution