A production process is designed to fill boxes with an average of 20 ounces of cereal. The population of filling weights is normally distributed with a standard deviation of 4 ounces.
a. Calculate the centerline, the upper control limit (UCL), and the lower control limit (LCL) for the x¯x¯ chart if samples of 15 boxes are taken. (Round the value for the centerline to the nearest whole number and the values for the UCL and LCL to 3 decimal places.)