Question 1: A manufacturer of wood screws periodically examines screws heads for the presence or absence of burrs. Subgroups of 300 screws are selected and examined using a carefully designed procedure. The collected data is as follows:
|
Observation
|
Number of Screws with Burrs
|
|
1
|
19
|
|
2
|
16
|
|
3
|
11
|
|
4
|
6
|
|
5
|
22
|
|
6
|
2
|
|
7
|
4
|
|
8
|
7
|
|
9
|
5
|
|
10
|
27
|
|
11
|
7
|
|
12
|
13
|
|
13
|
17
|
|
14
|
29
|
|
15
|
1
|
|
16
|
2
|
|
17
|
19
|
|
18
|
28
|
|
19
|
24
|
|
20
|
23
|
a- Find the centerline (show your calculations)
b- Find the control limits (show your calculations)
c- Use MINITAB to develop the appropriate control chart
d- Are there any special causes of variation? Which observations?
e- What to do next?