2) Five data entry operators work at the data processing department of the Royal Bank. Each day for 30 days, the number of defective records in a sample of 250 records typed by these operators has been noted, as follows:

Sample
No. No.
Defective Sample
No. No.
Defective Sample
No. No.
Defective
1 18 11 17 21 7
2 5 12 12 22 5
3 16 13 6 23 19
4 4 14 7 24 10
5 11 15 13 25 11
6 8 16 10 26 8
7 12 17 4 27 12
8 4 18 6 28 9
9 6 19 12 29 6
10 16 20 3 30 13

• Establish 3σ upper and lower control limits.
• Why can the lower control limit not be a negative number?
• The industry standards for the upper and lower control limits are 0.10 and 0.01, respectively. What does this imply about Royal Bank’s own standards?