The National Country (NC) is a mail-order company that processes thousands of mail and telephone orders each week. They have a customer service number to handle customer order problems and monitor the number of complaints. The total number of complaint calls the customer service department has received for each of the last 20 weeks are shown below. The average number of complaints has been 24 in the past year.

1. Construct R control chart(s) to monitor customer service quality using 3 sigma limits.

(8 marks)

1. Show clearly on the graph the values for the center line, UCL and LCL. (8 marks)
2. Is the process in control? Justify your answerbriefly. (4 marks)

Weeks	No. of Complaint	Weeks	No. of Complaint
1	27	11	26
2	15	12	30
3	36	13	33
4	28	14	35
5	19	15	25
6	23	16	19
7	21	17	12
8	16	18	17
9	29	19	18
10	35	20	26