Occasionally, a random sample of three packages of Skittles is selected from the output and weighed, to be sure that the system is under control. Here are data on five such samples. Measurements are in ounces. Sample 1 2 3 4 5 1 3.61 3.65 3.56 3.49 3.64 2 3.58 3.62 3.58 3.65 3.54 3 3.62 3.49 3.67 3.45 3.61 a. What type of control chart should be used to monitor the process dispersion