Problem 10-12 The time needed for checking in at a hotel is to be investigated. Historically, the process has had a standard deviation equal to .146. The means of 39 samples of n = 21 are Sample Sample Sample Sample 31 11 12 Mean 3.84 3.82 3.89 3. 86 32 Mean 3.86 3.90 3.83 3.81 3.84 3.83 3.87 3.88 3.84 33 Mean 3.88 3.86 3.88 3.81 3.83 3.86 3.82 3.86 3.84 3.87 3.88 Mean 3.88 3.76 3.83 3.77 3.86 3.80 3.84 3.79 3.85 3.90 3.81 3.86 3.80 3.98 3.96 a-1. Construct an X-chart for this process with three-sigma limits. (Do not round intermediate calculations. Round your answers to 2 decimal places.) UCL LCL a-2. Is the process in control? Yes O No