1. The following are quality control data for a manufacturing process at Kensprt Chemical Company. The data show the temperature in degrees centigrade at five points in time during the manufacturing cycle. The company is interested in using quality control charts in monitoring the temperature of its manufacturing cycle. Construct an X bar and R chart and indicate what its tells you about the process.
Sample X bar R
1 95.72 1.0
2 95.24 .9
3 95.18 .8
4 95.44 .4
5 95.46 .5
6 95.32 1.1
7 95.40 .9
8 95.44 .3
9 95.08 .2
10 95.50 .6
11 95.80 .6
12 95.22 .2
13 95.56 1.3
14 95.22 .5
15 95.04 .8
16 95.72 1.1
17 94.82 .6
18 95.46 .5
19 95.60 .4
20 95.74 .6
2. An airline operates a call center to handle customer questions and complaints. the airline monitors a sample of calls to help ensure that the service being offered is of high quality. The random samples of 100 calls each were monitored under normal conditions. The center can be thought of as being in control when these 10 samples were taken. The number of calls in each sample not resulting in a satisfactory resolution for the customer is as follows:
4 5 3 2 3 3 4 6 4 7
a. What is an estimate of the proportion of calls not resulting in a satisfactory outcome for the customer when the center is in control?
b. Construct the upper and lower limits for a p chart for the process.
c. With the results in part b. what is your conclusion if a sample of 100 calls has 12 calls not resulting in a satisfactory outcome for the customer?
3. A national study by Harris Interactive, Inc., evaluated the top technology companies and their reputations. The following shows how technology companies ranked in reputation and how the companies ranked in percentage of respondents who said they would purchase the company's stock. A positive rank correlation is anticipated because it seems reasonable to expect that a company with a higher reputation would have the more desirable stock to purchase.
A. compute the rank correlation between reputation and stock purchase.
B. Test for a significant positive rank correlation. What is the p-value?
C. At a= .05 , what is your conclusion?
4. A student organization surveyed both current students and recent graduates to obtain information on the quality of teaching at a particular university. An analysis of the responses provided the following teaching-ability rankings. Do the rankings given by the current students agree with the rankings given by the recent graduates? Use a=.10 and test for a significant rank correlation.