Question

Supplementary Problem 18.15

A bottled-water company has been randomly inspecting bottles of water to determine whether they are acceptable for delivery and sale. The inspectors are looking at water quality, bottle condition, and seal tightness. A series of 10 random samples of 50 bottles each is taken. Some bottles are rejected. Use the following information on the number of bottles from each batch that were rejected as being out of compliance to construct a p chart.

Sample

N

Number out of Compliance

1	50	3
2	50	11
3	50	7
4	50	2
5	50	5
6	50	8
7	50	0
8	50	9
9	50	1
10	50	6

create a p chart.

Answer 1

The proportion of non confirming bottles in each of the 10 samples drawn here is computed as:

Sample	N	Number out of Compliance	Proportion of out of compliance bottles
1	50	3	0.06
2	50	11	0.22
3	50	7	0.14
4	50	2	0.04
5	50	5	0.1
6	50	8	0.16
7	50	0	0
8	50	9	0.18
9	50	1	0.02
10	50	6	0.12

The given last column was plotted against the sample number to get the p-chart as:

The various metrics above are computed here as: