1. The Great North Woods Clothing Company sells specialty outdoor clothing through its catalog. A quality problem that generates customer complaints occurs when a warehouse employee fills an order with the wrong items. The company has decided to implement a process control plan by inspecting the ordered items after they have been obtained from the warehouse and before they have been packaged. The company has taken 30 samples (during a 30-day period), each for 100 orders, and recorded the number of defective orders in each sample, as follows:
Sample |
Number of Defectives |
Sample |
Number of Defectives |
1 |
12 |
16 |
6 |
2 |
14 |
17 |
3 |
3 |
10 |
18 |
7 |
4 |
16 |
19 |
10 |
5 |
18 |
20 |
14 |
6 |
19 |
21 |
18 |
7 |
14 |
22 |
22 |
8 |
20 |
23 |
26 |
9 |
18 |
24 |
20 |
10 |
17 |
25 |
24 |
11 |
9 |
26 |
18 |
12 |
11 |
27 |
19 |
13 |
14 |
28 |
20 |
14 |
12 |
29 |
17 |
15 |
7 |
30 |
18 |
2. The Great North Woods Clothing Company is a mail-order company that processes thousands of mail and telephone orders each week. It has a customer service number to handle customer order problems, inquiries, and complaints. The company wants to monitor the number of customer calls that can be classified as complaints. The total number of complaint calls the customer service department has received for each of the last 30 weekdays are shown as follows:
Day |
Complaint Calls |
Day |
Complaint Calls |
1 |
27 |
16 |
19 |
2 |
15 |
17 |
12 |
3 |
38 |
18 |
17 |
4 |
41 |
19 |
18 |
5 |
19 |
20 |
26 |
6 |
23 |
21 |
31 |
7 |
21 |
22 |
14 |
8 |
16 |
23 |
18 |
9 |
33 |
24 |
26 |
10 |
35 |
25 |
27 |
11 |
26 |
26 |
35 |
12 |
42 |
27 |
20 |
13 |
40 |
28 |
12 |
14 |
35 |
29 |
16 |
15 |
25 |
30 |
15 |
a. Construct a c-chart for this process with 3σcontrol limits and indicate if the process was out of control at any time.
b. What nonrandom (i.e., assignable) causes might result in the process being out of control?