The time to replace vehicle wiper blades at a service center was monitored using a mean and a range chart. Six samples of n = 20 observations have been obtained and the sample means and ranges computed:

The time to replace vehicle wiper blades at a service center was monitored using a mean and a range chart. Six samples of n=20 observations have been obtained and the sample means and ranges computed: Factors for three-sigma control limits for x charts a. Using the factors in the above table, determine upper and lower limits for mean chart. (Do not round intermediate calculations. Round your mean value to 3 decimal places and range value to 4 decimal places.) b. Is the process in control? Yes No