As a manager for T.G.I. Friday's one of your main concerns is customer wait time. Over the past week you have measured the amount of time it takes from when the customer places his/her order with the server until the food is delivered, see reverse side for 250 data points (there is an Excel spreadsheet in Brighspace with the observations). Your district manager has asked you to perform SPC on the data to see, amongst other things, if the process is in control and whether or not you can meet customer requirements. With this in mind, develop a memo to your boss that addresses the following issues: a.) Create 25 subgroups and calculate the average and range for each subgroup. Discuss the strategy you used to create your subgroups. NOTES - 1.) Do NOT use all 250 observations... remember SPC charts are based on random sampling 2.) You do NOT have to show hand calculations for the means and ranges of these subgroups b.) Develop both an R-chart and an X-bar chart. Show and label all calculations. Are both variables in control? Justify your answer. c.) Use a cause and effect diagram to show scenarios that detail potential assignable causes that could lead to an x-bar chart to be out of control - use the " 4M method" when doing this. Are there any ways you could try to prevent those "errors" from happening? d.) Customers expect an average wait time of 25 minutes. They are willing to accept times between 20 and 30 minutes. Is your process capable of meeting these targets? Please show and label all calculations