Question 20 (4 points) Which of the following is true about using control charts to monitor process performance to ensure quality? 0 The R-chart monitors the process lower limit conformance O A process should be halted and investigated if the sample result is between the upper control Limit and the lower control limit 0 The X-bar chart monitors process upper limit conformance O The process is \"under control\" if the sample observations form a random pattern within the control limits