1. Suppose we are testing the difference between two proportions at the 0.05 level of significance. If the
computed
z
is
1.07, what is our decision?
A. Reject the null hypothesis
B. Do not reject the null hypothesis
C. Take a larger sample
D. Reserve judgment
2. The net weights (in grams) of a sample of bottles filled by a machine manufactured by Edne, and the net
weights of a sample filled by a similar machine manufactured by Orno, Inc., are:
Edne: 5, 8, 7, 6, 9 and 7
Orno: 8, 10, 7, 11, 9, 12, 14 and 9
Testing the claim at the 0.05 level that the mean weight of the bottles filled by the Orno machine is greater than
the mean weight of the bottles filled by the Edne machine, what is the critical value? Assume equal standard
deviations for both samples.
3. When is it appropriate to use the paired difference
t
test?
4. Administering the same test to a group of 15 students and a second group of 15 students to see which group
scores higher is an example of
5. 20 randomly selected statistics students were given 15 multiplechoice questions and 15 openended
questions – all on the same material. The professor was interested in determining which type of questions the
students scored higher. This experiment is an example of
A. a one sample test of means.
B. a two sample test of means.
C. a paired
t
test.
D. a test of proportions.
USE the following situation for Questions 6 and 7:
Of 250 adults who were administered the J2P2
antivirus 187 did not show symptoms of the disease that it guarded against; of 100 children who were
administered the antivirus, 66 did not show symptoms of the disease.
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6. Using the 0.1 significance level and the alternate hypothesis
π
1
not equal to
π
2
, what is the null
hypothesis?
7. What test statistic should we use?
Use the following situation for Questions 8 – 15:
A national manufacturer of ball bearings is
experimenting with two different processes for producing precision ball bearings. It is important that the
diameters be as close as possible to an industry standard. The output from each process is sampled and the
average error from the industry standard is calculated. The results are presented below.
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 Fall '10
 Roy
 Statistics, Null hypothesis, Statistical hypothesis testing, A. Reject Ho

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