chapter 10s review questions to attempt plus model answer
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CHAPTER 10: REVIEW QUESTIONS QUALITY CONTROL AND MODEL ANSWER4.Checkout time at a supermarket is monitored using a mean and a range chart. Six samples of
n = 20 observations have been obtained and the sample means and ranges computed:
Sample Mean Range Sample Mean Range
13.06.4243.13.46
23.15.5053.06.46
33.11.4163.09.45
a. Using the factors in Table 10.3, determine upper and lower limits for mean and range charts.b. Is the process in control? MODEL ANSWER
4.
n = 20
A2 = 0.18 EQ \O(=,X) = 3.10; Mean Chart: EQ \O(=,X) ( A2 EQ \O((,R) = 3.1 ( 0.18(0.45)
D3 = 0.41 EQ \O((,R) = 0.45 = 3.1 ( .081
D4 = 1.59Hence, UCL is 3.181
and LCL is 3.019. All means are within these limits.
Range Chart: UCL is D4 EQ \O((,R) = 1.59(0.45) = .7155
LCL is D3 EQ \O((,R) = 0.41(0.45) = .1845
QUESTION 6 TO ATTEMPTThe table below shows the fillweights of toothpaste tubes on a filling machine. The time between samples is 20 minutes; 24 samples are taken during the 8-hour production shift. The samples are of size n=4.Table: Data on fillweight of Toothpaste Tubes
Sample
Fillweight (gms)
1
22.1
21.9
21.7
22.0
2
22.0
22.2
21.7
21.6
3
22.2
21.9
22.0
22.0
4
21.6
22.2
22.3
22.0
5
22.2
21.9
22.1
22.4
6
22.2
22.2
21.9
22.3
7
22.2
22.2
22.1
21.8
8
22.0
22.0
22.0
22.1
9
21.9
22.2
21.7
21.5
10
22.2
21.8
21.8
22.2
11
21.9
21.7
22.5
22.0
12
22.3
22.0
21.9
21.8
13
21.8
22.2
22.2
21.7
14
22.0
21.9
22.1
22.1
15
22.2
21.9
22.1
22.2
16
22.2
21.9
22.1
22.1
17
22.2
21.9
21.9
22.0
18
21.9
22.0
22.0
21.8
19
22.2
22.2
21.8
21.8
20
22.1
22.1
22.0
21.7
21
21.5
21.7
21.9
21.9
22
21.8
21.8
21.7
21.5
23
21.5
21.9
21.7
21.8
24
21.5
21.6
21.7
21.7
a.Calculate both the X-bar chart and R-chart control limits.b.Draw both charts and plot the above data.
c.Comment on the process variability.