A machine fills boxes with cereal. The labeled weight is 9oz. The quality control department sampled three boxes every day for four days. The samples are as follows (You may download the table from the following Excel file to facilitate calculation The X double bar of samples is The R bar of the samples is The lower control limit ( LCL) of X bar chart is (refer to the table below if necessary). The upper control limit (UCL) of R bar chart is (refer to the table below if necessary) (Keep two decimal points)