Question

A quality control inspector has taken ten samples of size four packets each from a potato chips company. The contents of the sample are given below, Calculate the control limits for the mean and range chart.

Sample Number	Observations
	1	2	3	4
1	12.5	12.3	12.6	12.7
2	12.8	12.4	12.4	12.8
3	12.1	12.6	12.5	12.4
4	12.2	12.6	12.5	12.3
5	12.4	12.5	12.5	12.5
6	12.3	12.4	12.6	12.6
7	12.6	12.7	12.5	12.8
8	12.4	12.3	12.6	12.5
9	12.6	12.5	12.3	12.6
10	12.1	12.7	12.5	12.8

(Given for n = 4, A₂ = 0.729, D₃ = 0 and D₄ = 2.282)

Answer 1

Sample Number	Observations				\(\overline {X}\)	R
	1	2	3	4
1	12.5	12.3	12.6	12.7	12.53	0.4
2	12.8	12.4	12.4	12.8	12.6	0.4
3	12.1	12.6	12.5	12.4	12.4	0.5
4	12.2	12.6	12.5	12.3	12.4	0.4
5	12.4	12.5	12.5	12.5	12.48	0.1
6	12.3	12.4	12.6	12.6	12.48	0.3
7	12.6	12.7	12.5	12.8	12.65	0.3
8	12.4	12.3	12.6	12.5	12.45	0.3
9	12.6	12.5	12.3	12.6	12.5	0.3
10	12.1	12.7	12.5	12.8	12.53	0.7
Total					125.02	3.7