Reference no: EM13537593

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?

Question 2: A given model of large radar dish represents the area of opportunity in which nonconformities may occur. Results of quality check for 25 radar assemblies are as follows:

Radar Assembly Number	Number of Nonconformities
1	25
2	60
3	28
4	65
5	91
6	56
7	40
8	54
9	90
10	44
11	62
12	81
13	70
14	75
15	24
16	50
17	70
18	56
19	21
20	88
21	34
22	82
23	53
24	102
25	64

a- Determine the centerline (show your calculations)

b- Determine the control limits (show your calculations)

c- Use MINITAB to develop the appropriate control chart

d- Are there any indications of lack of control?

e- What to do next?

Question 3: Workers at a packaging operation shovels a granular product from a large pile into sacks that are then sealed and placed on pallets for shipping. A sequence of 25 subgroups each consisting of the weights of 5 sacks has been recorded as follows:

	Observations
Subgroup #	Sack 1	Sack 2	Sack 3	Sack 4	Sack 5
1	35.4	35.6	34.8	34.7	34.8
2	36	35.6	34.9	34.8	35.9
3	35.2	35	35	35.4	35.1
4	34.8	35.8	35.2	35	34.9
5	34.2	35	36.1	34.9	35.1
6	36	35	35.2	34.8	34.9
7	36.1	34.9	34.5	35	35.1
8	35.1	35	35.6	34.9	36.2
9	35	35.6	36.1	34.8	35.6
10	35.4	35.8	36	34.2	36
11	35.2	35.3	35.2	35.9	34.8
12	35.9	36	35.1	35.1	35.6
13	35.2	35.6	35	34.9	35
14	35.2	35.6	35.8	35	35.1
15	34.9	34.8	35	35.2	34.9
16	35.2	35.3	35.2	35.6	35.1
17	35.6	35.8	35.2	35.4	34.9
18	35.2	35.6	35.4	35.6	35.2
19	34.7	34.9	35.6	35.2	35
20	35	35.1	35.6	35	35.1
21	35.6	35	35.8	35.2	34.6
22	34.9	35.1	35.6	35	35.2
23	35.9	36	35.2	36	35.2
24	35.2	35.1	35.4	34.9	35.1
25	35.2	35.2	35.1	35.6	34.9

a- What is the appropriate control chart that can be used by the quality engineer in this case?

b- Determine the control limits (show your calculations)

c- Construct the appropriate control chart for the data above using MINITAB.

d- Is the process in-control? If not, when does the out-of-control behavior occur?

e- If the process is found to be out of control, drop the out-of-control points and use MINITAB to re-construct the control chart.

f-  Is the process now in-control? If not, what to do next?

Question 4: Viscosity is one of the important quality characteristics of paste ink used in printing presses.  A viscosity measure is taken at the end of production of each batch of ink. Viscosity measures for 50 consecutive batches have been recorded as follows:

Sample	Viscosity			Sample	Viscosity
1	305			26	291
2	274			27	301
3	290			28	290
4	314			29	290
5	291			30	308
6	315			31	306
7	301			32	292
8	298			33	279
9	306			34	276
10	305			35	285
11	270			36	296
12	296			37	275
13	307			38	299
14	284			39	301
15	280			40	294
16	264			41	312
17	299			42	289
18	270			43	278
19	275			44	288
20	276			45	299
21	294			46	270
22	313			47	308
23	304			48	298
24	310			49	294
25	271			50	306

a- What is the appropriate control chart that can be used by the quality engineer in this case?

b- Determine the control limits (show your calculations)

c- Construct the appropriate control chart for the data above using MINITAB.

d- Is the process in-control? If not, when does the out-of-control behavior occur?

e- If the process is found to be out of control, drop the out-of-control points and use MINITAB to re-construct the control chart.

f-  Is the process now in-control? If not, what to do next?