Amanager wishes to build a control chart for a process. A total of five (05) samples are collected with four (04) observations within each sample. The sample means (X-bar) are; 15.36,14.61,16.36,20.28, and 15.77 respectively. Also, the corresponding ranges are; 10.79,8.37, 2.81,8.17, and 3.31 respectively. The lower and upper control limits of the x-bar chart are ,respectively . 16.55, 11.47 O b. None is correct O c. 11.59,21.36 O d. 12.40, 19.72 18.55, 13.47 O e