please solve part b, Thanks

3. The time required to serve customers at the drive-by window is an important order qualifier factor in competing with other coffee shops in the U.S. city. The mean time to process a customer order at the peak demand period is 5 minutes. The standard deviation is 1.5 minutes. The sample size is six customers. Morning Brew Coffee realizes that its process variability is in control, so it needs to determine if the process average is also in control. (Check chapter 3) a. Calculate or design your process average control limit and x-chart. You can skip the x-chart drawing but give me the upper and lower control limits. b. After several weeks of sampling, two successive samples came in at 3.70 and 3.68 minutes, respectively. Is the customer service process statistical control