CHAPTER 10—COMPARISONS INVOLVING MEANS, EXPERIMENTAL
DESIGN, AND ANALYSIS OF VARIANCE
1.
Maxforce, Inc. manufactures racquetball racquets by two different manufacturing processes (A and B).
Because the management of this company is interested in estimating the difference between the
average time it takes each process to produce a racquet, they select independent samples from each
process. The results of the samples are shown below.
Process A
Process B
Sample Size
32
35
Sample Mean (in minutes)
43
47
Population Variance (
σ
2
)
64
70
a.
Develop a 95% confidence interval estimate for the difference between the average times of
the two processes.
b.
Is there conclusive evidence to prove that one process takes longer than the other? If yes,
which process? Explain.
2.
Consider the following results for two samples randomly taken from two normal populations with
equal variances.
Sample I
Sample II
Sample Size
28
35
Sample Mean
48
44
Population Standard Deviation
9
10
a.
Develop a 95% confidence interval for the difference between the two population means.
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 Spring '10
 Finance
 Statistics, Normal Distribution, Variance, Interest, Sample Size Sample

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