AnderSet Laboratories produces rough lenses that will ultimately be ground into precision lenses for use in laboratory

Question:

AnderSet Laboratories produces rough lenses that will ultimately be ground into precision lenses for use in laboratory equipment. The company has developed the following thickness measures, based on 15 samples of four lenses that were taken when the process was under control:

a. Use these data to calculate X and R and set up the appropriate control charts.
b. Can the process be “under control” in statistical terms but still fail to meet the needs of AnderSet’s customers? Explain, using a numerical example.