A factory that packages food products in metal cans has installed an ink jet to spray a date code onto the bottom of the cans. Sometimes the process does not work correctly and the date codes are either missing or illegible. A p-chart is to be constructed based on the data set in DS 16.6.2, which records the number of defective date-codes found in random samples of n = 250 cans taken at k = 25 time points.
(a) Does it appear that the process was out of control at any time while this data set was collected?
(b) What p-chart would you recommend be used to monitor future samples of date codes?
(c) How many defective date codes would need to be discovered in a future sample for the process to be considered to be out of control?