An X-bar control chart is to be established based on the in-control baseline with =600 and = 12 , and n=4. The control limits are established based on Type I error rate of 0.002. Assume the measurements are normally distributed. (a) What are the appropriate control limits and center line? (1.5 point) (b) Assume the mean shift is 18 , what is Type II error rate for detecting this mean shift by using this control chart? (1 point)