UNIT 3 TEST STA 2023 MCGRAW HILL |
2026 UPDATED STUDY GUIDE WITH
PRACTICE QUESTIONS, ANSWERS, AND
RATIONALES
| GRADED A+ | GUARANTEED SUCCESS
Updated 2026 Questions and Answers
100% Verified Exam Prep and Comprehensive
Rationales Included
,We draw a random sample of size 25 from the normal [11.7019, 13.2981]
population with variance 2.4. If the sample mean is 12.5,
what is a 99% confidence interval for the population
mean? The confidence interval for the population mean is computed as formula69.mml.
Use z table.
A politician wants to estimate the percentage of people 151
who like his new slogan. Given that no prior estimate of
the population proportion is available, what is the For a desired margin of error E, the minimum sample size n required to estimate a
minimum sample size such that the margin of error is no formula276.mml confidence interval for the population proportion is computed as
more than 0.08 for a 95% confidence interval? formula277.mml is a reasonable estimate of formula278.mml in the planning stage.
Use z table.
The t distribution table lists tdf values for selected lower- False
tail probabilities and degrees of freedom df.
The t distribution table lists tdf values for selected upper-tail probabilities and
degrees of freedom df.
A confidence interval provides a value that, with a certain False
measure of confidence, is the population parameter of
interest. A confidence interval provides a range of values that, with a certain level of
confidence, contains the population parameter of interest.
Suppose we wish to find the required sample size to find 0.50
a 90% confidence interval for the population proportion
with the desired margin of error. If there is no rough For a desired margin of error E, the minimum sample size n required to estimate a
estimate formula259.mml of the population proportion, formula256.mml confidence interval for the population proportion is computed as
what value should be assumed for formula259.mml? formula257.mml is a reasonable estimate of formula258.mml in the planning stage.
Use z table.
When the required sample size calculated by using a Round the result of the calculation up to the nearest whole number.
formula is not a whole number, what is the best choice
for the required sample size? To be conservative, always round up noninteger values of the calculated required
sample size.
Statisticians like precision in their interval estimates. A low A larger sample size reduces the margin of error.
margin of error is needed to achieve this. Which of the
following supports this when selecting sample sizes? If we are able to increase the size of the sample, the larger nreduces the margin
of error for the interval estimates.
The minimum sample size n required to estimate a 10.7688
population mean with 95% confidence and the desired
margin of error 1.5 was found to be 198. Which of the
following is the approximate value of the assumed For a desired margin of error E, the minimum sample size n required to estimate a
estimate of the population standard deviation? 1formula226.mml confidence interval for the population mean is computed as
1formula227.mml 1formula228.mml is a reasonable estimate of 1formula229.mml in
the planning stage. Because the required sample size is rounded up the following
is correct: 1formula230.mml . It can be derived that 1formula231.mml Use z table.
, Which of the following is the necessary condition for Normality of the estimator
creating confidence intervals for the population mean?
For the confidence interval, the estimator formula55.mml must be at least
approximately normally distributed. By the central limit theorem, even when the
population is not normally distributed, this condition is satisfied as long as the
sample size 1formula56.mml
We draw a random sample of size 25 from the normal [11.7019, 13.2981]
population with variance 2.4. If the sample mean is 12.5,
what is a 99% confidence interval for the population
mean? The confidence interval for the population mean is computed as formula69.mml.
Use z table.
What is the most typical form of a calculated confidence Point estimate ± Margin of error
interval?
It is common to construct a confidence interval as Point estimate ± Margin of
error.
In an examination of holiday spending (known to be [$44.7967, $63.2033]
normally distributed) of a sample of 16 holiday shoppers
at a local mall, an average of $54 was spent per hour of Because the population standard deviation is unknown use tdf distribution. The
shopping. Based on the current sample, the standard confidence interval of the population mean is computed as formula116.mml. Use t
deviation is equal to $21. Find a 90% confidence interval table.
for the population mean level of spending per hour.
The tdf distribution consists of a family of distributions False
where the actual shape of each one depends on the
degrees of freedom, df. For lower values of df, the tdf The tdf distribution consists of a family of distributions where the actual shape of
distribution is similar to the z distribution. 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 2.92 + 2.093 (0.16/sqrt(20))
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 Because the population standard deviation is unknown use tdf distribution. The
interval for the mean GPA of all accounting students at confidence interval of the population mean is computed as formula100.mml. Use t
this university. table.
A confidence interval provides a value that, with a certain False
measure of confidence, is the population parameter of
interest. 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 False
size n, the width of the confidence interval for the
population mean is narrower, the greater the population For a given confidence levelformula6.mmland sample size n, the width of the
standard deviation σ. confidence interval for the population mean is wider, the greater the population
standard deviation σ.
2026 UPDATED STUDY GUIDE WITH
PRACTICE QUESTIONS, ANSWERS, AND
RATIONALES
| GRADED A+ | GUARANTEED SUCCESS
Updated 2026 Questions and Answers
100% Verified Exam Prep and Comprehensive
Rationales Included
,We draw a random sample of size 25 from the normal [11.7019, 13.2981]
population with variance 2.4. If the sample mean is 12.5,
what is a 99% confidence interval for the population
mean? The confidence interval for the population mean is computed as formula69.mml.
Use z table.
A politician wants to estimate the percentage of people 151
who like his new slogan. Given that no prior estimate of
the population proportion is available, what is the For a desired margin of error E, the minimum sample size n required to estimate a
minimum sample size such that the margin of error is no formula276.mml confidence interval for the population proportion is computed as
more than 0.08 for a 95% confidence interval? formula277.mml is a reasonable estimate of formula278.mml in the planning stage.
Use z table.
The t distribution table lists tdf values for selected lower- False
tail probabilities and degrees of freedom df.
The t distribution table lists tdf values for selected upper-tail probabilities and
degrees of freedom df.
A confidence interval provides a value that, with a certain False
measure of confidence, is the population parameter of
interest. A confidence interval provides a range of values that, with a certain level of
confidence, contains the population parameter of interest.
Suppose we wish to find the required sample size to find 0.50
a 90% confidence interval for the population proportion
with the desired margin of error. If there is no rough For a desired margin of error E, the minimum sample size n required to estimate a
estimate formula259.mml of the population proportion, formula256.mml confidence interval for the population proportion is computed as
what value should be assumed for formula259.mml? formula257.mml is a reasonable estimate of formula258.mml in the planning stage.
Use z table.
When the required sample size calculated by using a Round the result of the calculation up to the nearest whole number.
formula is not a whole number, what is the best choice
for the required sample size? To be conservative, always round up noninteger values of the calculated required
sample size.
Statisticians like precision in their interval estimates. A low A larger sample size reduces the margin of error.
margin of error is needed to achieve this. Which of the
following supports this when selecting sample sizes? If we are able to increase the size of the sample, the larger nreduces the margin
of error for the interval estimates.
The minimum sample size n required to estimate a 10.7688
population mean with 95% confidence and the desired
margin of error 1.5 was found to be 198. Which of the
following is the approximate value of the assumed For a desired margin of error E, the minimum sample size n required to estimate a
estimate of the population standard deviation? 1formula226.mml confidence interval for the population mean is computed as
1formula227.mml 1formula228.mml is a reasonable estimate of 1formula229.mml in
the planning stage. Because the required sample size is rounded up the following
is correct: 1formula230.mml . It can be derived that 1formula231.mml Use z table.
, Which of the following is the necessary condition for Normality of the estimator
creating confidence intervals for the population mean?
For the confidence interval, the estimator formula55.mml must be at least
approximately normally distributed. By the central limit theorem, even when the
population is not normally distributed, this condition is satisfied as long as the
sample size 1formula56.mml
We draw a random sample of size 25 from the normal [11.7019, 13.2981]
population with variance 2.4. If the sample mean is 12.5,
what is a 99% confidence interval for the population
mean? The confidence interval for the population mean is computed as formula69.mml.
Use z table.
What is the most typical form of a calculated confidence Point estimate ± Margin of error
interval?
It is common to construct a confidence interval as Point estimate ± Margin of
error.
In an examination of holiday spending (known to be [$44.7967, $63.2033]
normally distributed) of a sample of 16 holiday shoppers
at a local mall, an average of $54 was spent per hour of Because the population standard deviation is unknown use tdf distribution. The
shopping. Based on the current sample, the standard confidence interval of the population mean is computed as formula116.mml. Use t
deviation is equal to $21. Find a 90% confidence interval table.
for the population mean level of spending per hour.
The tdf distribution consists of a family of distributions False
where the actual shape of each one depends on the
degrees of freedom, df. For lower values of df, the tdf The tdf distribution consists of a family of distributions where the actual shape of
distribution is similar to the z distribution. 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 2.92 + 2.093 (0.16/sqrt(20))
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 Because the population standard deviation is unknown use tdf distribution. The
interval for the mean GPA of all accounting students at confidence interval of the population mean is computed as formula100.mml. Use t
this university. table.
A confidence interval provides a value that, with a certain False
measure of confidence, is the population parameter of
interest. 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 False
size n, the width of the confidence interval for the
population mean is narrower, the greater the population For a given confidence levelformula6.mmland sample size n, the width of the
standard deviation σ. confidence interval for the population mean is wider, the greater the population
standard deviation σ.
