©FYNDLAY 2024/2025 ALL RIGHTS RESERVED 12:27AM. A+
Math 221: Statistics Exam Questions And
Answers| Already Graded A+| Latest Update.
From a random sample of 58 businesses, it is found that the mean time the owner spends on
administrative issues each week is 21.69 with a population standard deviation of 3.23. What is
the 95% confidence interval for the amount of time spent on administrative issues?
A. (19.24, 24.14)
B. (21.78, 22.60)
C. (20.86, 22.52)
D. (20.71, 22.67) - Answer✔C. (20.86, 22.52)
If a confidence interval is given from 45.82 up to 55.90 and the mean is known to be 50.86,
what is the margin of error?
2.52
5.04
45.82
10.08 - Answer✔5.04
If a computer manufacturer needed a supplier that could produce parts that were very precise,
what characteristics would be better?
narrow confidence interval at low confidence level
narrow confidence interval at high confidence level
wide confidence interval with high confidence level
wide confidence interval with low confidence level - Answer✔narrow confidence interval at
high confidence level
Which of the following are most likely to lead to a wide confidence interval?
1
, ©FYNDLAY 2024/2025 ALL RIGHTS RESERVED 12:27AM. A+
small standard deviation
small sample size
large mean
large sample size - Answer✔small sample size
If you were designing a study that would benefit from data points with high values, you would
want the input variable to have:
a large sample size
a large mean
a large standard deviation
a large margin of error - Answer✔a large mean
The 95% confidence interval for these parts is 56.98 to 57.05 under normal operations. A
systematic sample is taken from the manufacturing line to determine if the production process
is still within acceptable levels. The mean of the sample is 56.99. What should be done about
the production line?
Keep the line operating as it is inside the confidence interval
Stop the line as it is inside the confidence interval
Stop the line as it is outside the confidence interval
Keep the line operating as it is outside the confidence interval - Answer✔Keep the line
operating as it is inside the confidence interval
In a sample of 57 temperature readings taken from the freezer of a restaurant, the mean is 29.6
degrees and the population standard deviation is 2.7 degrees. What would be the 80%
confidence interval for the temperatures in the freezer?
(31.90, 32.44)
(29.14, 30.06)
(24.25, 35.05)
(26.91, 32.31) - Answer✔(29.14, 30.06)
What is the 99% confidence interval for a sample of 36 seat belts that have a mean length of
85.6 inches long and a population standard deviation of 2.5 inches?
(80.6, 90.6)
(83.1, 88.1)
2
, ©FYNDLAY 2024/2025 ALL RIGHTS RESERVED 12:27AM. A+
(84.4, 86.8)
(84.5, 86.7) - Answer✔(84.5, 86.7)
If two samples A and B had the same mean and standard deviation, but sample A had a larger
sample size, which sample would have the wider 95% confidence interval?
Sample B as its sample is more dispersed
Sample B as it has the smaller sample
Sample A as it comes first
Sample A as it has the larger sample - Answer✔Sample B as it has the smaller sample
Why might a company use a lower confidence interval, such as 80%, rather than a high
confidence interval, such as 99%?
They are in the medical field, so cannot be so precise
They make computer parts where they are too small for higher accuracy
They track the migration of fish where accuracy is not as important
They make children's toys where imprecision is expected - Answer✔They track the migration of
fish where accuracy is not as important
Determine the minimum sample size required when you want to be 95% confident that the
sample mean is within two units of the population mean. Assume a population standard
deviation of 4.3 in a normally distributed population.
20
22
16
18 - Answer✔18
Determine the minimum sample size required when you want to be 99% confident that the
sample mean is within 0.50 units of the population mean. Assume a population standard
deviation of 2.9 in a normally distributed population.
130
224
223
129 - Answer✔224
3
Math 221: Statistics Exam Questions And
Answers| Already Graded A+| Latest Update.
From a random sample of 58 businesses, it is found that the mean time the owner spends on
administrative issues each week is 21.69 with a population standard deviation of 3.23. What is
the 95% confidence interval for the amount of time spent on administrative issues?
A. (19.24, 24.14)
B. (21.78, 22.60)
C. (20.86, 22.52)
D. (20.71, 22.67) - Answer✔C. (20.86, 22.52)
If a confidence interval is given from 45.82 up to 55.90 and the mean is known to be 50.86,
what is the margin of error?
2.52
5.04
45.82
10.08 - Answer✔5.04
If a computer manufacturer needed a supplier that could produce parts that were very precise,
what characteristics would be better?
narrow confidence interval at low confidence level
narrow confidence interval at high confidence level
wide confidence interval with high confidence level
wide confidence interval with low confidence level - Answer✔narrow confidence interval at
high confidence level
Which of the following are most likely to lead to a wide confidence interval?
1
, ©FYNDLAY 2024/2025 ALL RIGHTS RESERVED 12:27AM. A+
small standard deviation
small sample size
large mean
large sample size - Answer✔small sample size
If you were designing a study that would benefit from data points with high values, you would
want the input variable to have:
a large sample size
a large mean
a large standard deviation
a large margin of error - Answer✔a large mean
The 95% confidence interval for these parts is 56.98 to 57.05 under normal operations. A
systematic sample is taken from the manufacturing line to determine if the production process
is still within acceptable levels. The mean of the sample is 56.99. What should be done about
the production line?
Keep the line operating as it is inside the confidence interval
Stop the line as it is inside the confidence interval
Stop the line as it is outside the confidence interval
Keep the line operating as it is outside the confidence interval - Answer✔Keep the line
operating as it is inside the confidence interval
In a sample of 57 temperature readings taken from the freezer of a restaurant, the mean is 29.6
degrees and the population standard deviation is 2.7 degrees. What would be the 80%
confidence interval for the temperatures in the freezer?
(31.90, 32.44)
(29.14, 30.06)
(24.25, 35.05)
(26.91, 32.31) - Answer✔(29.14, 30.06)
What is the 99% confidence interval for a sample of 36 seat belts that have a mean length of
85.6 inches long and a population standard deviation of 2.5 inches?
(80.6, 90.6)
(83.1, 88.1)
2
, ©FYNDLAY 2024/2025 ALL RIGHTS RESERVED 12:27AM. A+
(84.4, 86.8)
(84.5, 86.7) - Answer✔(84.5, 86.7)
If two samples A and B had the same mean and standard deviation, but sample A had a larger
sample size, which sample would have the wider 95% confidence interval?
Sample B as its sample is more dispersed
Sample B as it has the smaller sample
Sample A as it comes first
Sample A as it has the larger sample - Answer✔Sample B as it has the smaller sample
Why might a company use a lower confidence interval, such as 80%, rather than a high
confidence interval, such as 99%?
They are in the medical field, so cannot be so precise
They make computer parts where they are too small for higher accuracy
They track the migration of fish where accuracy is not as important
They make children's toys where imprecision is expected - Answer✔They track the migration of
fish where accuracy is not as important
Determine the minimum sample size required when you want to be 95% confident that the
sample mean is within two units of the population mean. Assume a population standard
deviation of 4.3 in a normally distributed population.
20
22
16
18 - Answer✔18
Determine the minimum sample size required when you want to be 99% confident that the
sample mean is within 0.50 units of the population mean. Assume a population standard
deviation of 2.9 in a normally distributed population.
130
224
223
129 - Answer✔224
3
