Assignment:
1. Mary Beth Marrs, the manager of an apartment complex, feels overwhelmed by the number of complaints she is receiving. Below is the check sheet she has kept for the past 12 weeks. Develop a Pareto chart using this information. What recommendations would you make?
2. Twelve samples, each containing live pans, were taken from a process that produces steel rods at Emmanuel Kodzi's factory. The length of each rod in the samples was determined. The results were tabulated and sample means and ranges were computed. The results were:
|
Sample
|
Sample Mean (in).
|
Range(in).
|
|
1
|
10.002
|
0.001
|
|
2
|
10.002
|
0.014
|
|
3
|
9.991
|
0.007
|
|
4
|
10.006
|
0.022
|
|
5
|
9.997
|
0.013
|
|
6
|
9.999
|
0.012
|
|
7
|
10.001
|
0.008
|
|
8
|
10.005
|
0.013
|
|
9
|
9.995
|
0.004
|
|
10
|
10.001
|
0.011
|
|
11
|
10.001
|
0.014
|
|
12
|
10.006
|
0.009
|
a) Determine the upper and lower control limits and the overall means for t-charts and R-charts.
b) Draw the charts and plot the values of the sample means and ranges.
c) Do the data indicate a process that is in control?
d) Why or why not?
3. Jamison Kovach Supply Company manufactures paper clips and other office products. Although inexpensive, paper clips have provided the firm with a high margin of profitability. Sample size is 200. Results are given for the last 10 samples:
|
Samples
|
1
|
2
|
3
|
4
|
5
|
6
|
7
|
8
|
9
|
10
|
|
Defectives
|
5
|
7
|
4
|
4
|
6
|
3
|
5
|
6
|
2
|
8
|
a) Establish upper and lower control limits for the control chart and graph the data.
b) Has the process been in control?
c) If the sample site were 100 instead, how would your limits and conclusions change?