The milling machine in the fabrication department of your company produces a very important part for the products you sell. You are given the following historical data on the machine (from a SAMPLE of n = 25 weeks): Machine Number of parts Breakdowns/week Produced/week (X) (Y) average # average # of of machine breakdowns/week: produced/week: parts X bar 50 Y bar 170 standard deviation. of # of machine standard deviation of # of breakdowns/week: parts produced/week: Sx-15 Sy=40 n=25 n=25 What is the symbol we used to represent the population standard deviation for the number of breakdowns for this machine in a week? Do you know the value of this parameter? If so, what is it?