In a fabric manufacturing factory, the quality control process using control charts from SPC. In an hour there are a total of 5 samples are taken each having 4 observations regarding the thickness of fabric in-measured in millimeters. In a particular hour, the sample means (X-bar) are noted to be: 172.11, 219.58, 208.24, 112.44, and 123.30 respectively. In the same sample, the corresponding ranges are: 13.17, 13.38, 15.34, 13.04, and 13.02 respectively What are the lower and upper control limits for the X-bar chart? a. 146.01, 157.87 b. 144.78, 159.11 c. None is correct O d. 157.21, 177.05 e. 143.55, 165.47 Of. 142.92, 160.66