A process manager wants to use control charts to control their process. They have decided that each sample should have 4 observations. The number of standard deviations the manager wants to use is 3. The manager found that the average range of the samples is 5. The grand average of the samples is 6.0. The standard deviation of the observations is 2. The manager took 20 samples to use to calculate the control limits. The formulas used to calculate the control limits is: UCL Xbar bar + 2 In this example, UCL = =