The following data are tensile strengths, in pounds, for a sample of string for industrial use made at a plant. Construct a control chart for the mean, using groups of 5 observations each. Test for statistical control of the process mean.

5, 6, 4, 6, 5, 7, 7, 7, 6, 5, 3, 5, 5, 5, 6, 5, 5, 6, 7, 7, 7, 7, 6, 7, 5, 5, 5, 6, 7, 7, 7, 7, 7, 5, 5, 6, 4, 6, 6, 6, 7, 6, 6, 6, 6, 6, 7, 5, 7, 6