Problem 10-3 (Static) The time in minutes to replace vehicle wiper blades at a service center was…

Problem 10-3 (Static)
The time in minutes to replace vehicle wiper blades at a service center was monitored using a mean and a range chart. Six samples of n = 20 observations were obtained and the sample means and ranges were computed:
Sample
Mean
Range
1
3.06
.42
2
3.15
.50
3
3.11
.41
4
3.13
.46
5
3.06
.46
6
3.09
.45
Click here for the Excel Data File
Factors for three-sigma control limits for x¯ and R charts
FACTORS FOR R CHARTS
Number of Observations in Subgroup, n
Factor for x¯ Chart, A2
Lower Control Limit, D3
Upper Control Limit, D4
2
1.88
0
3.27
3
1.02
0
2.57
4
0.73
0
2.28
5
0.58
0
2.11
6
0.48
0
2.00
7
0.42
0.08
1.92
8
0.37
0.14
1.86
9
0.34
0.18
1.82
10
0.31
0.22
1.78
11
0.29
0.26
1.74
12
0.27
0.28
1.72
13
0.25
0.31
1.69
14
0.24
0.33
1.67
15
0.22
0.35
1.65
16
0.21
0.36
1.64
17
0.20
0.38
1.62
18
0.19
0.39
1.61
19
0.19
0.40
1.60
20
0.18
0.41
1.59
a. Using the factors in the above table, determine upper and lower limits for mean and range charts. (Do not round intermediate calculations. Round your mean value to 3 decimal places and range value to 4 decimal places.)
a1. Is the process in control? multiple choice 1 The process is in control. The process is not in control.
b. The time in minutes needed to assemble security cameras at a production facility was recorded for eight samples of 15 observations each, and means and ranges were computed. Using factors from the above table, compute control limits for the means and ranges. (Round your answers to 3 decimal places.)
Sample
Mean
Range
1
7.10
.52
2
6.92
.48
3
7.25
.50
4
7.54
.51
5
7.21
.46
6
8.01
.55
7
7.80
.53
8
7.63
.49
b1. Is the process is in control. multiple choice 2 The process is in control. The process is not in control.