Assignment Due 6/14/2000
(Click here for
previous assignments)
Review (and correct as appropriate) your work on
Exam 1. Some of the material is likely to appear on Exam 2,
which is scheduled for 6/20 (Thursday of next week), and you will
definitely see this material also on the final exam.
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Review your statistics notes concerning hypothesis
testing and then try to work the following exercises:
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A company manufactures gas vent tubes that have
averaged 9.80 cm in length with a standard deviation (s)
of 0.60 cm. (Tube lengths are approximately normally
distributed.) SPC charts are to be set up for a sampling
process that involves sampling 9 tubes each hour. The purpose
of these limits is to facilitate the detection of when the process
becomes out of control (i.e., when the process average shifts in
either direction from the value of m
= 9.80 cm). If any sample average is less than the lower
control limit (LCL) or greater than the upper control limit (UCL),
it will be concluded that the overall process average is no longer
9.80 cm; the process will then be adjusted. This essentially
constitutes performing a hypothesis test that is to be performed
each time a sample is taken.
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State the null and alternative hypotheses for
this test.
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Sketch the sampling distribution for this test
and indicate the rejection region(s) on the sketch.
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What is the decision rule for this test if a
level of significance (a)
of 0.0028 or better is desired?
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Suppose a sample is taken and the observed
average tube length is 9.30 cm. What is the
appropriate conclusion for this test? Write your answer using a
single sentence that refers to your decision rule and the
calculated value of the test statistic.
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KIVZ’s station manager is concerned about the
Boise economy. She has proposed that the overall average
income for households in the area differs from the national average
of $32,000. Conduct a hypothesis test to see if the data (soon to be
gathered via a survey of Boise area residents) provide sufficient
evidence to prove her claim at a level of significance of a
= 5%.
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State the null and alternative hypotheses for
this test.
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Sketch the sampling distribution for this test
and indicate the rejection region(s) on the sketch.
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What is the decision rule for this test?
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Suppose a sample of 50 households is taken and
the observed average income is $37,800 with a standard deviation
of $21,350. What is the appropriate conclusion for this
test? Write your answer using a single sentence that
refers to your decision rule and the calculated value of the
test statistic.
Resume working on learning Deming's 14 Points.
Complete your reading of Chapter 5 in the text
and the corresponding material in the study guide. Work on answering
the Review Questions and attempt to identify the
text Exercises that involve control charting, but do not
try to work those exercises yet.
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