CHAPTER 12 SECTION 1: INFERENCE ABOUT A POPULATION
MULTIPLE CHOICE
1.
Researchers determined that 60 Kleenex tissues is the average number of tissues used during a cold.
Suppose a random sample of 100 Kleenex users yielded the following data on the number of tissues
used during a cold:
= 52 and
s
= 22. Suppose the test statistic does not fall in the rejection region at
= 0.05. Which of the following conclusions is correct?
a.
At
= 0.05, we do not reject
H
0
.
b.
At
= 0.05, we reject
H
0
.
c.
At
= 0.05, we accept
H
0
.
d.
Both a and c.
ANS:
A
PTS:
1
REF:
SECTION 12.1
2.
A robust estimator is one that is:
3.
For statistical inference about the mean of a single population when the population standard deviation
is unknown, the degrees for freedom for the
t
distribution equal
n
1 because we lose one degree of
freedom by using the:
4.
Researchers determined that 60 Kleenex tissues is the average number of tissues used during a cold.
Suppose a random sample of 100 Kleenex users yielded the following data on the number of tissues
used during a cold:
= 52 and
s
= 22. Suppose the alternative we wanted to test was
H
1
:
< 60. The
correct rejection region for
= 0.05 is:
5.
A random sample of size 15 taken from a normally distributed population revealed a sample mean of
75 and a sample variance of 25. The upper limit of a 95% confidence interval for the population mean
would equal:
a.
77.77
b.
72.23
c.
88.85
d.
77.27
ANS:
A
PTS:
1
REF:
SECTION 12.1
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6.
A major department store chain is interested in estimating the average amount its credit card customers
spent on their first visit to the chain's new store in the mall. Fifteen credit card accounts were randomly
sampled and analyzed with the following results:
= $50.50 and
s
2
= 400. A 95% confidence interval
for the average amount the credit card customers spent on their first visit to the chain's new store in the
mall is:
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 Spring '11
 Kim
 Statistics, Normal Distribution, Standard Deviation, Statistical hypothesis testing

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