Every employee in a check-processing department goes through a four-month training period, after which the employee is responsible for their operation. The work of one employee who has been on the job for eight months is being studied. Table 8-15 shows the number of errors and the number of items sampled over a period of two months. The first 16 samples were each chosen from 400 items, and the remaining 9 samples were each chosen from 300 items. Determine whether the employee's performance can be judged stable. Comment on the capability of the employee.
TABLE 8-15

tem mpl 400 400 400 300 300 300 000 300 300 300 300 300 886465807453 456789012345 2937604756491 0123 S-1234567891111