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Chapter 7 (Sections 7.2 & 7.3) Hand-in HW
Show all work on this paper.
1.
Thompson and Thompson is a steel bolts manufacturing company.
Their current steel bolts have a mean
diameter of
128
millimeters, and a standard deviation of
8
. If a random sample of
31
steel bolts is
selected, what is the probability that the sample mean would differ from the population mean by more
than
0.9
millimeters?
Round your answer to four decimal places.
2.
Thompson and Thompson is a steel bolts manufacturing company.
Their current steel bolts have a mean
diameter of
141
millimeters, and a standard deviation of
7
. If a random sample of
39
steel bolts is
selected, what is the probability that the sample mean would be greater than
141.4
millimeters?
Round
your answer to four decimal places.
3.
The mean per capita income is
24,787
dollars per annum with a
variance
of
169,744
.What is the
probability that the sample mean would differ from the true mean by less than
42
dollars if a sample of
412
persons is randomly selected?
Round your answer to four decimal places.
