# Project and Quality Management Questions

Pages: 1 (337 words) Published: April 20, 2015
Please submit your HW (Hardcopy) at the end of lecture OR to my office (L214)

QMDS 400 Project and Quality Management
HW#2

DUE 6:00pm 18 Nov 2014

Name:_______________________ Student ID:___________________

Note:

Late submission will NOT be accepted!

PROBLEMS

P1. After a number of complaints about its directory assistance, a telephone company examined samples of calls to determine the frequency of wrong numbers given to callers. Each sample consisted of 100 calls. The results to date are shown below. Analyze the data using an appropriate control chart with a 5% risk of Type I error. Is the process stable (i.e., in control) based on the limits?

Sample
# of errors

1
5

2
3

3
5

4
7

5
4

6
6

7
8

8
4

9
5

10
9

11
3

12
4

13
5

14
6

15
6

16
7

P2. A process had the following service times (in minutes) for 20 randomly selected customers:
SAMPLE
1

2

3

4

4.5

4.6

4.5

4.7

4.2

4.5

4.6

4.6

4.2

4.4

4.4

4.8

4.3

4.7

4.4

4.5

4.3

4.3

4.6

4.9

a) Determine the mean of each sample.
b) Construct control charts for means and ranges using the table on page 26 (Slides 8). Is the process in control?
c) If the process has a known mean of 4.4 and a known standard deviation of 0.18, what would 3-sigma control limits be for the mean chart? Are any sample means beyond the control limits?
P3. A process that makes chocolate candy bars has an output that is normally distributed with a mean of 6 oz. and a standard deviation of 0.01 oz. A job is to be run that requires 200 candy bars.
a) Determine three sigma control limits for an x-bar chart assuming a sample size of 10. b) If specifications are 5.98 to 6.02, what run size should be used for this job so that the expected number of good candy bars is 200, assuming the process is in control?