Weights of pieces of tile made in Arizona in April 2007 (in ounces) are as follows: 2.5,

Question:

Weights of pieces of tile made in Arizona in April 2007 (in ounces) are as follows: 2.5, 2.66, 2.8, 2.3, 2.5, 2.33, 2.41, 2.88, 2.54, 2.11, 2.26, 2.3, 2.41, 2.44, 2.17, 2.52, 2.55, 2.38, 2.89, 2.9, 2.11, 2.12, 2.13, 2.16. Create an R chart for these data, using subgroups of size 4. Is the process variation under control?