Q1) There are 4 auto body shops in Bangor, Maine, and all claim to promptly serve customers. To check if there is any difference in service, customers are arbitrarily chosen from each repair shop and their waiting times in days are recorded. Output from a statistical software package is:
|
Summary
|
|
Groups
|
Count
|
Sum
|
Average
|
Variance
|
|
Body Shop A
|
3
|
15.4
|
5.133
|
0.323333
|
|
Body Shop B
|
4
|
32
|
8
|
1.43333
|
|
Body Shop C
|
5
|
25.2
|
5.04
|
0.748
|
|
Body Shop D
|
4
|
25.9
|
6.475
|
0.595833
|
|
ANOVA
|
|
Source of Variation
|
SS
|
df
|
MS
|
F
|
p-value
|
|
Between Groups
|
23.37321
|
3
|
7.791069
|
9.612506
|
0.001632
|
|
Within Groups
|
9.726167
|
12
|
0.810514
|
|
|
|
Total
|
33.09938
|
15
|
|
|
|
Is there evidence to suggest difference in mean waiting times at the four body shops? Use.05 significance level.
Q2) Three assembly lines are used to make a certain component for an airliner. To study production rate, a random sample of six hourly periods is selected for each assembly line and the number of components produced in these periods for each line is recorded. Output from a statistical software package is
|
Summary
|
|
Groups
|
Count
|
Sum
|
Average
|
Variance
|
|
Line A
|
6
|
250
|
41.66667
|
0.266667
|
|
Line B
|
6
|
260
|
43.33333
|
0.666667
|
|
Line C
|
6
|
249
|
41.5
|
0.7
|
Create a 99 percent confidence interval for difference in means between Line B and Line C