X control charts are used to maintain control of the manufacture of the cases used to house a generic brand of personal computer. Separate charts are maintained for length, width, and height. The length chart has UCL  20.5 inches, LCL  19.5 inches, and a target value of 20 inches. This chart is based on using subgroups of size 4 and threesigma limits. However, the customer’s specifications require that the target length should be 19.75 inches with a tolerance of 0.75 inch. What percentage of the cases shipped will fall outside the customer’s specifications?