OPRE 3360 EXAM 3 Questions With
Complete Solutions
/.An estimate of a population parameter that provides an interval believed to contain the
value of the parameter is known as the
a. confidence level
b. interval estimate
c. parameter value
d. population estimate
/.As the sample size increases, the margin of error
a. increases
b. decreases
c. stays the same
d. None of the other answers is correct.
/.The Z value for a 97.8% confidence interval estimation is
a. 2.02
b. 1.96
c. 2.00
d. 2.29
/.It is known that the variance of a population equals 1,936. A random sample of 121
has been taken from the population. The margin of error in a 95% confidence interval is:
a. 7.84
b. 31.36
c. 344.96
d. 1,936
/.A random sample of 144 observations has a mean of 20, a median of 21, and a mode
of 22. The population standard deviation is known to equal 4.8. The 95.44% confidence
interval for the population mean is
a. 15.2 to 24.8
b. 19.2 to 20.8
c. 19.216 to 20.784
d. 21.2 to 22.8
/.To estimate a population mean, the sample size needed to provide a margin of error of
2 or less with a 95% confidence interval when the population standard deviation equals
11 is
a. 10
b. 11
, c. 116
d. 117
/.Scenario 1: To estimate the average time spent on the computer terminals per student
at a local university, data were collected from a sample of 81 business students over a
one-week period. Assume the population standard deviation is 1.2 hours.
The standard error of the mean is
a. 7.5
b. 0.014
c. 0.160
d. 0.133
/.Scenario 1: To estimate the average time spent on the computer terminals per student
at a local university, data were collected from a sample of 81 business students over a
one-week period. Assume the population standard deviation is 1.2 hours.
With a 0.95 probability, the margin of error is approximately
a. 0.26
b. 1.96
c. 0.21
d. 1.64
/.Scenario 1: To estimate the average time spent on the computer terminals per student
at a local university, data were collected from a sample of 81 business students over a
one-week period. Assume the population standard deviation is 1.2 hours.
If the sample mean is 9 hours, then the 95% confidence interval is approximately
a. 7.04 to 110.96 hours
b. 7.36 to 10.64 hours
c. 7.80 to 10.20 hours
d. 8.74 to 9.26 hours
/.Scenario 2: A random sample of 81 automobiles traveling on a section of an interstate
showed an average speed of 60 mph. The speed distribution of all cars on this section
of the highway is normally distributed, with a standard deviation of 13.5 miles per hour.
If we are interested in determining an interval estimate for 𝜇 at 86.9% confidence, the Z
value to use is
a. 1.96
b. 1.31
c. 1.51
d. 2.00
Complete Solutions
/.An estimate of a population parameter that provides an interval believed to contain the
value of the parameter is known as the
a. confidence level
b. interval estimate
c. parameter value
d. population estimate
/.As the sample size increases, the margin of error
a. increases
b. decreases
c. stays the same
d. None of the other answers is correct.
/.The Z value for a 97.8% confidence interval estimation is
a. 2.02
b. 1.96
c. 2.00
d. 2.29
/.It is known that the variance of a population equals 1,936. A random sample of 121
has been taken from the population. The margin of error in a 95% confidence interval is:
a. 7.84
b. 31.36
c. 344.96
d. 1,936
/.A random sample of 144 observations has a mean of 20, a median of 21, and a mode
of 22. The population standard deviation is known to equal 4.8. The 95.44% confidence
interval for the population mean is
a. 15.2 to 24.8
b. 19.2 to 20.8
c. 19.216 to 20.784
d. 21.2 to 22.8
/.To estimate a population mean, the sample size needed to provide a margin of error of
2 or less with a 95% confidence interval when the population standard deviation equals
11 is
a. 10
b. 11
, c. 116
d. 117
/.Scenario 1: To estimate the average time spent on the computer terminals per student
at a local university, data were collected from a sample of 81 business students over a
one-week period. Assume the population standard deviation is 1.2 hours.
The standard error of the mean is
a. 7.5
b. 0.014
c. 0.160
d. 0.133
/.Scenario 1: To estimate the average time spent on the computer terminals per student
at a local university, data were collected from a sample of 81 business students over a
one-week period. Assume the population standard deviation is 1.2 hours.
With a 0.95 probability, the margin of error is approximately
a. 0.26
b. 1.96
c. 0.21
d. 1.64
/.Scenario 1: To estimate the average time spent on the computer terminals per student
at a local university, data were collected from a sample of 81 business students over a
one-week period. Assume the population standard deviation is 1.2 hours.
If the sample mean is 9 hours, then the 95% confidence interval is approximately
a. 7.04 to 110.96 hours
b. 7.36 to 10.64 hours
c. 7.80 to 10.20 hours
d. 8.74 to 9.26 hours
/.Scenario 2: A random sample of 81 automobiles traveling on a section of an interstate
showed an average speed of 60 mph. The speed distribution of all cars on this section
of the highway is normally distributed, with a standard deviation of 13.5 miles per hour.
If we are interested in determining an interval estimate for 𝜇 at 86.9% confidence, the Z
value to use is
a. 1.96
b. 1.31
c. 1.51
d. 2.00
