I need help, I don't know how to do this.

The McGranger Mortgage Company is interested in monitoring the performance of the mortgage process. Fifteen samples of five completed mortgage transactions each were taken during a period when the process was believed to be in control. The times to complete the transactions were measured. The McGranger Mortgage Company made some changes to the process and undertook a process capability study. The following data were obtained for 15 samples of size 5. Based on the individual observations, management estimated the process standard deviation to be 3.22 (days) for use in the process capability analysis. The lower and upper specification limits (in days) for the mortgage process times were 5 and 20. 3 5 6 8 9 11 12 13 Sample Mean Range 1 9 7 2 10 6 4 14 10 11 7 15 7 11 9 11 8 16 10 12 10 14 14 7 5 13 11 14 12 9 15 7 10 12 3 13 4 a. Calculate the process capability index and the process capability ratio values. The process capability index Cpk = (Enter your response rounded to three decimal places.)