STAT 2023 MODULE 4 TEST ST PETERSBURG
COLLEGE 2026 COMPREHENSIVE STATISTICS
REVIEW QUESTIONS AND SOLUTIONS
VERIFIED
◉ What is the most typical form of a calculated confidence interval?
Answer: Point estimate ± Margin of error
It is common to construct a confidence interval as Point estimate ±
Margin of error.
◉ In an examination of holiday spending (known to be normally
distributed) of a sample of 16 holiday shoppers at a local mall, an
average of $54 was spent per hour of shopping. Based on the current
sample, the standard deviation is equal to $21. Find a 90%
confidence interval for the population mean level of spending per
hour. Answer: [$44.7967, $63.2033]
Because the population standard deviation is unknown use tdf
distribution. The confidence interval of the population mean is
computed as formula116.mml. Use t table.
,◉ The tdf distribution consists of a family of distributions where the
actual shape of each one depends on the degrees of freedom, df. For
lower values of df, the tdf distribution is similar to the z distribution.
Answer: False
The tdf distribution consists of a family of distributions where the
actual shape of each one depends on the degrees of freedom, df. As
df increases, the tdf distribution becomes more similar to the z
distribution; it is identical to the z distribution when df is infinity.
◉ The GPA of accounting students in a university is known to be
normally distributed. A random sample of 20 accounting students
results in a mean of 2.92 and a standard deviation of 0.16. Construct
the 95% confidence interval for the mean GPA of all accounting
students at this university. Answer: 2.92 + 2.093 (0.16/sqrt(20))
Because the population standard deviation is unknown use tdf
distribution. The confidence interval of the population mean is
computed as formula100.mml. Use t table.
◉ A confidence interval provides a value that, with a certain
measure of confidence, is the population parameter of interest.
Answer: False
,A confidence interval provides a range of values that, with a certain
level of confidence, contains the population parameter of interest.
◉ For a given confidence levelformula5.mmland sample size n, the
width of the confidence interval for the population mean is
narrower, the greater the population standard deviation σ. Answer:
False
For a given confidence levelformula6.mmland sample size n, the
width of the confidence interval for the population mean is wider,
the greater the population standard deviation σ.
◉ Which of the following are one-tailed tests? Answer: Both Ho:μ ≤
10, HA:μ > 10 and Ho:μ ≥ 400, HA:μ < 400
A two-tailed test is defined when the alternative hypothesis includes
the sign "≠". A one-tailed test involves a null hypothesis that can be
rejected only on one side of hypothesized value.
◉ Vermont-based Green Mountain Coffee Roasters dominates the
market for single-serve coffee in the United States, with its
subsidiary Keurig accounting for approximately 70% of sales
("Rivals Try to Loosen Keurig's Grip on Single-Serve Coffee Market,"
Chicago Tribune, February 26, 2011). But Keurig's patent on K-cups,
the plastic pods used to brew the coffee, is expected to expire in
2012, allowing other companies to better compete. Suppose a
, potential competitor has been conducting blind taste tests on its
blend and finds that 47% of consumers strongly prefer its French
Roast to that of Green Mountain Coffee Roasters. After tweaking its
recipe, the competitor conducts a test with 144 tasters, of which 72
prefer its blend. The competitor claims that its new blend is
preferred by more than 47% of consumers to Green Mountain Coffee
Roasters' French Roast. What is the value of the appropriate test
statistic to test this c Answer: z = 0.721
When testing the population proportion, the value of the test
statistic is computed as formula54.mml
◉ The national average for an eighth-grade reading comprehension
test is 73. A school district claims that its eighth-graders outperform
the national average. In testing the school district's claim, how does
one define the population parameter of interest? Answer: The mean
score on the eighth-grade reading comprehension test
Hypothesis testing is used to resolve conflicts between two
competing hypotheses on a particular population parameter of
interest.
COLLEGE 2026 COMPREHENSIVE STATISTICS
REVIEW QUESTIONS AND SOLUTIONS
VERIFIED
◉ What is the most typical form of a calculated confidence interval?
Answer: Point estimate ± Margin of error
It is common to construct a confidence interval as Point estimate ±
Margin of error.
◉ In an examination of holiday spending (known to be normally
distributed) of a sample of 16 holiday shoppers at a local mall, an
average of $54 was spent per hour of shopping. Based on the current
sample, the standard deviation is equal to $21. Find a 90%
confidence interval for the population mean level of spending per
hour. Answer: [$44.7967, $63.2033]
Because the population standard deviation is unknown use tdf
distribution. The confidence interval of the population mean is
computed as formula116.mml. Use t table.
,◉ The tdf distribution consists of a family of distributions where the
actual shape of each one depends on the degrees of freedom, df. For
lower values of df, the tdf distribution is similar to the z distribution.
Answer: False
The tdf distribution consists of a family of distributions where the
actual shape of each one depends on the degrees of freedom, df. As
df increases, the tdf distribution becomes more similar to the z
distribution; it is identical to the z distribution when df is infinity.
◉ The GPA of accounting students in a university is known to be
normally distributed. A random sample of 20 accounting students
results in a mean of 2.92 and a standard deviation of 0.16. Construct
the 95% confidence interval for the mean GPA of all accounting
students at this university. Answer: 2.92 + 2.093 (0.16/sqrt(20))
Because the population standard deviation is unknown use tdf
distribution. The confidence interval of the population mean is
computed as formula100.mml. Use t table.
◉ A confidence interval provides a value that, with a certain
measure of confidence, is the population parameter of interest.
Answer: False
,A confidence interval provides a range of values that, with a certain
level of confidence, contains the population parameter of interest.
◉ For a given confidence levelformula5.mmland sample size n, the
width of the confidence interval for the population mean is
narrower, the greater the population standard deviation σ. Answer:
False
For a given confidence levelformula6.mmland sample size n, the
width of the confidence interval for the population mean is wider,
the greater the population standard deviation σ.
◉ Which of the following are one-tailed tests? Answer: Both Ho:μ ≤
10, HA:μ > 10 and Ho:μ ≥ 400, HA:μ < 400
A two-tailed test is defined when the alternative hypothesis includes
the sign "≠". A one-tailed test involves a null hypothesis that can be
rejected only on one side of hypothesized value.
◉ Vermont-based Green Mountain Coffee Roasters dominates the
market for single-serve coffee in the United States, with its
subsidiary Keurig accounting for approximately 70% of sales
("Rivals Try to Loosen Keurig's Grip on Single-Serve Coffee Market,"
Chicago Tribune, February 26, 2011). But Keurig's patent on K-cups,
the plastic pods used to brew the coffee, is expected to expire in
2012, allowing other companies to better compete. Suppose a
, potential competitor has been conducting blind taste tests on its
blend and finds that 47% of consumers strongly prefer its French
Roast to that of Green Mountain Coffee Roasters. After tweaking its
recipe, the competitor conducts a test with 144 tasters, of which 72
prefer its blend. The competitor claims that its new blend is
preferred by more than 47% of consumers to Green Mountain Coffee
Roasters' French Roast. What is the value of the appropriate test
statistic to test this c Answer: z = 0.721
When testing the population proportion, the value of the test
statistic is computed as formula54.mml
◉ The national average for an eighth-grade reading comprehension
test is 73. A school district claims that its eighth-graders outperform
the national average. In testing the school district's claim, how does
one define the population parameter of interest? Answer: The mean
score on the eighth-grade reading comprehension test
Hypothesis testing is used to resolve conflicts between two
competing hypotheses on a particular population parameter of
interest.
