STAT 420
Fall 2010
Homework #3
(10 points)
(due Friday, September 17, by 3:00 p.m.)
1.
4.17
(a), (b)
An engineer is investigating the strength of concrete beams made from four types
of cement and employing three curing processes.
The breaking strengths are
measured and are presented below.
Curing
Cement
Type
Process
A
B
C
D
1
14
6
22
10
2
15
8
20
7
3
10
7
18
7
a)
List an appropriate model and the underlying assumptions for this situation.
b)
Construct the ANOVA table and test for differences in cement types and curing
processes.
Assume a 5percent significance level.
2.
4.18
(a), (b)
Referring back to Problem
4.17
, suppose that two additional beams are made for
each combination of cement type and curing process and the breaking strengths
determined.
The complete layout follows.
Curing
Cement
Type
Process
A
B
C
D
1
14, 14, 10
6, 9, 7
22, 25, 20
10, 11, 13
2
15, 12, 10
8, 4, 11
20, 15, 19
7, 9, 10
3
10, 8, 10
7, 4, 7
18, 21, 22
7, 6, 6
a)
Specify an appropriate model for this situation and the underlying assumptions.
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 Spring '08
 Stepanov
 Statistics, Portland cement, Fert

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