Statistical Process Control (13+15 = 28 Questions) - ENGG381-14A Engineering Statistics (Task A, B, C) - 15 Questions done twice

Reference:Managing Quality: Integrating the Supply Chain, 4th Ed. By S. ThomasFoster

1. Interpret the following charts to determine if the processes are stable.

2. A production process for JMF Semicon is monitored using the x-bar and R charts. Ten samples of n=15 observations have been gathered with the following results:

Sample	Mean	Range
1	282	35
2	290	54
3	262	43
4	309	30
5	263	42
6	325	24
7	288	4
8	298	23
9	277	17
10	363	55

a. Develop a control chart and plot the means.

b. Is the process in control? Explain.

3. A finishing process packages assemblies into boxes. You have noticed variability in the boxes and desire to improve the process to fix the problem because some products fit too tightly into the boxes and others fit too loosely. Following are width measurements for the boxes. Using x-bar and R charts, plot and interpret the process.

Sample
1	2	3	4	5	6	7	8
82.21	82.73	82.39	82.19	82.37	82.01	82.79	82.70
82.15	81.84	82.13	82.73	82.36	82.10	82.73	82.69
82.25	82.25	82.26	82.27	82.34	82.79	82.74	82.76
82.01	82.27	82.52	82.34	81.98	81.62	82.74	82.72
82.15	82.44	82.44	82.43	82.01	81.64	82.73	82.75
82.15	82.44	82.37	82.27	81.89	82.16	82.76	82.74

4. A Rochester, New York firm produces grommets that have to fit into a slot in an assembly. Following are dimensions of grommets (in millimeters):

Sample	x
1	69	50	81	69	96
2	78	68	81	113	96
3	51	96	54	69	95
4	51	68	71	56	93
5	69	96	113	83	24

a. Using x-bar and R charts, determine if the process is in control.