Business Statistics

652 Business Statistics

TABLE 17.9

The proportion of defective pumps in a group of 100 water pumps

Sample n Defective Items Proportion ( p

i

)

1 100 5 0.05

2 100 6 0.06

3 100 3 0.03

4 100 2 0.02

5 100 4 0.04

6 100 5 0.05

7 100 7 0.07

8 100 8 0.08

9 100 2 0.02

10 100 4 0.04

11 100 5 0.05

12 100 8 0.08

13 100 9 0.09

14 100 3 0.03

15 100 4 0.04

16 100 5 0.05

17 100 1 0.01

18 100 3 0.03

19 100 6 0.06

20 100 2 0.02

21 100 5 0.05

22 100 3 0.03

23 100 4 0.04

24 100 7 0.07

25 100 8 0.08

Control limit (CL) =

0.0476p =

Upper control limit (UCL) =

3 0.1115

p

p + =

Lower control limit (LCL) =

3 – 0.0162

p

p − =

It is impossible to set –0.0162 defective items as the lower control limit. ...