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 8-23 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.