CISB FINAL EXAM 2025 QUESTIONS
AND ANSWERS
A confidence interval on the mean: (D) - ANS A)
Calculates a range of possible values for the population mean.
B)
Is needed when the population mean is unknown and it is difficult to collect all possible values
in the population.
C)
Uses a sample from the population to estimate the population mean.
D)
All options are true.
The point estimate when calculating a confidence interval on the population average is the
sample mean. - ANS True
Which of the following applies to a point estimate? (D) - ANS A)
The point estimate is the same as the population parameter.
B)
The point estimate is not needed to calculate a confidence interval.
C)
The point estimate will be the same as the population mean if the sample size exceeds 30.
D)
The point estimate is subject to sampling error and will almost always be different from the
population value.
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,A 95% confidence interval on the mean tells us that 95% of all possible samples will have the
population mean within the calculated range - ANS True
Graphing a 90% confidence interval on a normal curve: (C) - ANS A)
The 90% is placed to the right with 10% in the lower tail.
B)
The 90% is centered with 10% in each tail.
C)
The 90% is centered with 5% in each tail.
D)
The 90% is placed to the left with 10% in the upper tail.
Decreasing the level of confidence increases the width of confidence interval. - ANS False
The general format for a confidence interval is: (D) - ANS A)
point estimate +- z (standard deviation).
B)
point estimate +- (critical value)(standard deviation)
C)
margin of error +- (confidence coefficient) (standard error).
D)
point estimate +- (critical value)(standard error).
When calculating a confidence interval, the reason for using the t-distribution rather than the
normal distribution for the critical value is that the population standard deviation is unknown. -
ANS True
Which of the following statements is true with respect to the t-distribution? (D) - ANS A)
The t-distribution is symmetrical.
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, B)
The exact shape of the t-distribution depends on the number of degrees of freedom.
C)
The t-distribution is more spread out than the standard normal distribution.
D)
All options are correct.
The purpose of a pilot sample is: (D) - ANS A)
to provide a better idea of what the population mean will be.
B)
to save time and money instead of having to carry out a full sampling plan.
C)
to help clarify how the sampling process will be performed.
D)
to provide an idea of what the population standard deviation might be.
It is appropriate to use a t-score using the pilot sample size instead of z in following equation to
find the needed sample size? - ANS False
When calculating n-size based on a desired margin of error and confidence level, if you find that
n=45.2, you should round up to n=46 to make sure you have a sample size large enough. -
ANS False
In determining the required sample size when estimating a population proportion, it is
necessary to start with some idea of what that proportion is. - ANS True
When determining the sample size for a proportion, if you have no previous information
available to estimate p, then the best value to use is p = 0.5. - ANS True
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AND ANSWERS
A confidence interval on the mean: (D) - ANS A)
Calculates a range of possible values for the population mean.
B)
Is needed when the population mean is unknown and it is difficult to collect all possible values
in the population.
C)
Uses a sample from the population to estimate the population mean.
D)
All options are true.
The point estimate when calculating a confidence interval on the population average is the
sample mean. - ANS True
Which of the following applies to a point estimate? (D) - ANS A)
The point estimate is the same as the population parameter.
B)
The point estimate is not needed to calculate a confidence interval.
C)
The point estimate will be the same as the population mean if the sample size exceeds 30.
D)
The point estimate is subject to sampling error and will almost always be different from the
population value.
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,A 95% confidence interval on the mean tells us that 95% of all possible samples will have the
population mean within the calculated range - ANS True
Graphing a 90% confidence interval on a normal curve: (C) - ANS A)
The 90% is placed to the right with 10% in the lower tail.
B)
The 90% is centered with 10% in each tail.
C)
The 90% is centered with 5% in each tail.
D)
The 90% is placed to the left with 10% in the upper tail.
Decreasing the level of confidence increases the width of confidence interval. - ANS False
The general format for a confidence interval is: (D) - ANS A)
point estimate +- z (standard deviation).
B)
point estimate +- (critical value)(standard deviation)
C)
margin of error +- (confidence coefficient) (standard error).
D)
point estimate +- (critical value)(standard error).
When calculating a confidence interval, the reason for using the t-distribution rather than the
normal distribution for the critical value is that the population standard deviation is unknown. -
ANS True
Which of the following statements is true with respect to the t-distribution? (D) - ANS A)
The t-distribution is symmetrical.
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, B)
The exact shape of the t-distribution depends on the number of degrees of freedom.
C)
The t-distribution is more spread out than the standard normal distribution.
D)
All options are correct.
The purpose of a pilot sample is: (D) - ANS A)
to provide a better idea of what the population mean will be.
B)
to save time and money instead of having to carry out a full sampling plan.
C)
to help clarify how the sampling process will be performed.
D)
to provide an idea of what the population standard deviation might be.
It is appropriate to use a t-score using the pilot sample size instead of z in following equation to
find the needed sample size? - ANS False
When calculating n-size based on a desired margin of error and confidence level, if you find that
n=45.2, you should round up to n=46 to make sure you have a sample size large enough. -
ANS False
In determining the required sample size when estimating a population proportion, it is
necessary to start with some idea of what that proportion is. - ANS True
When determining the sample size for a proportion, if you have no previous information
available to estimate p, then the best value to use is p = 0.5. - ANS True
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