A shirt manufacturer buys cloth by the 100 yard roll from a supplier. For setting up a control chart to manage the irregularities (e.g., loose threads and tears) the following data was collected from a sample provided by the supplier.

SAMPLE 1 2 3 4 5 6 7 8 9 10 IRREGULARITIES 3 5 2 6 5 4 6 3 4 5

a. Using these data set up a c -chart with z 2.

b. Suppose the next fi ve rolls from the supplier had three, two, fi ve, three and seven irregularities. Is the supplier process under control?