STAT 2023 MODULE 4 TEST SOLUTIONS ST
PETERSBURG COLLEGE 2026 COMPLETE
QUESTIONS AND ANSWERS GRADED A+ FULL
SOLUTION
◉ When examining the possible outcome of an election, what type of
confidence interval is most suitable for estimating the current
support for a candidate? Answer: The confidence interval for the
population proportion
Sometimes the parameter of interest describes a population that is
qualitative rather than quantitative. The population proportion is
the essential descriptive measure of when the data type is
qualitative.
◉ How do the tdf and z distributions differ? Answer: The tdf
distribution has broader tails (it is flatter around zero).
The tdf distribution has broader tails than the z distribution.
,◉ If a random sample of size n is taken from a normal population
with a finite variance, then the statisticformula20.mmlfollows the tdf
distribution with (n −1) degrees of freedom, df. Answer: True
If a random sample of size n is taken from a normal population with
a finite variance, then the statisticformula21.mmlfollows the tdf
distribution with (n −1) degrees of freedom, df.
◉ We draw a random sample of size 25 from the normal population
with variance 2.4. If the sample mean is 12.5, what is a 99%
confidence interval for the population mean? Answer: [11.7019,
13.2981]
The confidence interval for the population mean is computed as
formula69.mml. Use z table.
◉ A politician wants to estimate the percentage of people who like
his new slogan. Given that no prior estimate of the population
proportion is available, what is the minimum sample size such that
the margin of error is no more than 0.08 for a 95% confidence
interval? Answer: 151
,For a desired margin of error E, the minimum sample size n required
to estimate a formula276.mml confidence interval for the population
proportion is computed as 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-tail
probabilities and degrees of freedom df. Answer: False
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
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.
◉ Suppose we wish to find the required sample size to find a 90%
confidence interval for the population proportion with the desired
margin of error. If there is no rough estimate formula259.mml of the
population proportion, what value should be assumed for
formula259.mml? Answer: 0.50
, For a desired margin of error E, the minimum sample size n required
to estimate a formula256.mml confidence interval for the population
proportion is computed as 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 formula is
not a whole number, what is the best choice for the required sample
size? Answer: Round the result of the calculation up to the nearest
whole number.
To be conservative, always round up noninteger values of the
calculated required sample size.
◉ Statisticians like precision in their interval estimates. A low
margin of error is needed to achieve this. Which of the following
supports this when selecting sample sizes? Answer: A larger sample
size reduces the margin of error.
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 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 estimate of the population standard deviation? Answer:
10.7688
PETERSBURG COLLEGE 2026 COMPLETE
QUESTIONS AND ANSWERS GRADED A+ FULL
SOLUTION
◉ When examining the possible outcome of an election, what type of
confidence interval is most suitable for estimating the current
support for a candidate? Answer: The confidence interval for the
population proportion
Sometimes the parameter of interest describes a population that is
qualitative rather than quantitative. The population proportion is
the essential descriptive measure of when the data type is
qualitative.
◉ How do the tdf and z distributions differ? Answer: The tdf
distribution has broader tails (it is flatter around zero).
The tdf distribution has broader tails than the z distribution.
,◉ If a random sample of size n is taken from a normal population
with a finite variance, then the statisticformula20.mmlfollows the tdf
distribution with (n −1) degrees of freedom, df. Answer: True
If a random sample of size n is taken from a normal population with
a finite variance, then the statisticformula21.mmlfollows the tdf
distribution with (n −1) degrees of freedom, df.
◉ We draw a random sample of size 25 from the normal population
with variance 2.4. If the sample mean is 12.5, what is a 99%
confidence interval for the population mean? Answer: [11.7019,
13.2981]
The confidence interval for the population mean is computed as
formula69.mml. Use z table.
◉ A politician wants to estimate the percentage of people who like
his new slogan. Given that no prior estimate of the population
proportion is available, what is the minimum sample size such that
the margin of error is no more than 0.08 for a 95% confidence
interval? Answer: 151
,For a desired margin of error E, the minimum sample size n required
to estimate a formula276.mml confidence interval for the population
proportion is computed as 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-tail
probabilities and degrees of freedom df. Answer: False
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
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.
◉ Suppose we wish to find the required sample size to find a 90%
confidence interval for the population proportion with the desired
margin of error. If there is no rough estimate formula259.mml of the
population proportion, what value should be assumed for
formula259.mml? Answer: 0.50
, For a desired margin of error E, the minimum sample size n required
to estimate a formula256.mml confidence interval for the population
proportion is computed as 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 formula is
not a whole number, what is the best choice for the required sample
size? Answer: Round the result of the calculation up to the nearest
whole number.
To be conservative, always round up noninteger values of the
calculated required sample size.
◉ Statisticians like precision in their interval estimates. A low
margin of error is needed to achieve this. Which of the following
supports this when selecting sample sizes? Answer: A larger sample
size reduces the margin of error.
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 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 estimate of the population standard deviation? Answer:
10.7688
