Question 1

University Hospital has been concerned with the number of errors found in its billing statements to patients. An audit of 100 bills per week over the past 12 weeks revealed the following number of errors:

Week 1 Errors 6

week 2 errors 8

week 3 errors 5

week 4 errors 5

week 5 errors 1

week 6 errors 4

week 7 errors 8

week 8 errors 5

week 9 errors 7

week 10 errors 8

week 11 errors 11

week 12 errors 4

(a) develop control charts with z=3

CL

UCL

LCL

(b) is the process in control?

Question 2

Breeze Toothpaste Company has been having a problem with some of the

tubes of toothpaste leaking. The tubes are packed in containers with 100 tubes each. Ten containers of toothpaste have been sampled. The following number of toothpaste tubes were found to have leaks:

Sample # of Leaky Tubes Sample # of Leaky Tubes

1 6 6 16

2 10 7 6

3 11 8 8

4 13 9 4

5 8 10 9

Total 91

1. Develop a p-chart with 3-sigma control limits:

(a) CL,

(b) UCL,

(c) LCL.

Note. If the lower control limit is negative, round the LCL to zero. (Round your answer to 3 decimal places)

1. Is the process in control?

Question 3

A quality control inspector has taken four samples with five observations each at the Beautiful Shampoo Company, measuring the volume of shampoo per bottle. If the average range for the four samples is 0.3 ounces and the average mean of the observations is 19.6 ounces, develop 3-sigma control limits for the bottling operation. (Round answers to 2 decimal places, e.g. 15.25.)

CL

UCL

LCL