Based on the historical data, standard deviation of the teller service process was found to be 1.5 minutes. Process mean is calculated as 3.8 minutes. If service time specifications are respectively 5 and 2 minutes, what is the process capability ratio (Cpk) and is process capable? 1-Show your solution for Cpk. 2- What does the Cpk you found say about the capability of the process with respect to spec limits? Your Answer: CPK (5-3.8)/3*1.5=0.86 for CPk of 0.86 indicates that the process is not cabable of meeting the specification.