West Battery has recently been receiving complaints from retailers that its 9-volt batteries are not lasting as long as other name brands. James W. head of the TQM program at West's Austin plant, believes there is no problem because his batteries have had an average life of 50 hours, about 10% longer than competitors' models. To raise the lifetime above this level would require a new level of technology not available to West. Nevertheless, he is concerned enough to set up hourly assembly line checks. Previously, after ensuring that the process was running properly, West took size n=5 samples of 9-volt batteries for each of 25 hours to establish the standards for control chart limits. Those samples are shown in the companion Excel file named "Battery_TQM.xlsx" (attached). With these limits established, West now takes 5 more hours of data, which are shown in the same aforementioned Excel file.

a. Construct X-bar and R charts based on the data of the first 25 hours. Comment on whether the process is in control.

b. Based on the control charts established using the first 25 hours' data, is the manufacturing process still in control during the recent 5 more hours?

Attachment:- Data.rar