Control charts for X and R are maintained on the shear strength in pounds of test spot welds. The subgroup size is 3. The values of X and R are computed for each subgroup. After 30 subgroups, X = 11,346 and ER = 873. (20 points) (X and R charts) A) compute the value of the 3-sigma (30) for the X and R charts and estimate the value of a on the assumption that the process is in statistical control. B) The specified strength for a weld is 529 lb. If the process is in statistical control and normally distributed, what can you conclude regarding its ability to meet this specification?