Problem 10-4 (Static)

Software upgrade times (in minutes) are being evaluated. Samples of five observations each have been taken, and the results are as listed.

SAMPLE
1	2	3	4	5	6
79.2	80.5	79.6	78.9	80.5	79.7
78.8	78.7	79.6	79.4	79.6	80.6
80.0	81.0	80.4	79.7	80.4	80.5
78.4	80.4	80.3	79.4	80.8	80.0
81.0	80.1	80.8	80.6	78.8	81.1

Click here for the Excel Data File

Factors for three-sigma control limits for xx and R charts

			FACTORS FOR R CHARTS
Number of Observations in Subgroup, n		Factor for xx Chart, A2	Lower Control Limit, D3	Upper Control Limit, D4
2		1.88	0	3.27
3		1.02	0	2.57
4		0.73	0	2.28
5		0.58	0	2.11
6		0.48	0	2.00
7		0.42	0.08	1.92
8		0.37	0.14	1.86
9		0.34	0.18	1.82
10		0.31	0.22	1.78
11		0.29	0.26	1.74
12		0.27	0.28	1.72
13		0.25	0.31	1.69
14		0.24	0.33	1.67
15		0.22	0.35	1.65
16		0.21	0.36	1.64
17		0.20	0.38	1.62
18		0.19	0.39	1.61
19		0.19	0.40	1.60
20		0.18	0.41	1.59

a. Using factors from above table, determine upper and lower control limits for mean and range charts. (Round your intermediate calculations and final answers to 2 decimal places. Leave no cells blank - be certain to enter "0" wherever required.)

b. Decide if the process is in control.

The process is in control.

The process is not in control.