Question

A textile manufacturer wants to set up a control chart for irregularities​ (e.g., oil​ stains, shop​ soil, loose​ threads, and​ tears) per 100 square yards of carpet. The following data were collected from a sample of twenty​ 100-square-yard pieces of​ carpet:

                                                                                                                                                                          

Sample	Irregularities	Sample	Irregularities	Sample	Irregularities	Sample	Irregularities
1	1111	6	55	11	66	16	55
2	77	7	1616	12	1010	17	1616
3	1212	8	1212	13	99	18	99
4	1717	9	1414	14	66	19	55
5	1515	10	55	15	99	20	1616

a. Using these​ data, set up a​ c-chart with

zequals=33.

The

UCL Subscript cUCLc

equals

nothing

and the

LCL Subscript cLCLc

equals

nothing.

​(Enter your responses rounded to two decimal​ places.)

Answer 1

C-bar = (11+7+12+17+15+5+16+12+14+5+6+10+9+6+9+5+16+9+5+16)/20

C-bar = 10.25

Z = 3

UCLc = C-bar + Z*(C-bar)^(1/2)

UCLc = 10.25 + 3*(10.25)^(1/2)

UCLc = 19.8547

UCLc = 19.85

LCLc = C-bar - Z*(C-bar)^(1/2)

LCLc = 10.25 - 3*(10.25)^(1/2)

LCLc = 0.6453

LCLc = 0.65

Below is the screenshot of the C-chart -