# Expert Answers

Question 1 Find the confidence interval for a population mean of 615 acres at a 90% level of confidence with a sample size of 52 and standard deviation of 27 acres. (Points : 1)

189 to 1190 acres

608.84 to 621.16 acres

452 to 4252 acres

172 to 2008 acres

Question 2.2. Which of the following distributions is most likely to approach a normal distribution? (Points : 1)

distribution of all possible sample means of sample size 90

distribution of all possible sample means of sample size 60

distribution of all possible sample means of sample size 120

distribution of all possible sample means of sample size 30

Question 3 A sample was taken of computation errors on an exam: 4, 7, 3, 8, 4, 4, 6, 1, 5, 2, 4, 8, 5, 4, 5. What value should be used for the population standard deviation? (Points : 1)

0.51

1.99

none, since the population standard deviation should never be estimated

1.92

Question 5.5. Confidence interval estimates of a population parameter ________. (Points : 1)

provide a range of values within which the true value of the parameter is believed to be

specify a value that accurately predicts the population parameter

eliminates the effect of sampling error

are used solely to estimate the value of population variance

Question 6.6. All of the following are reasons why random sampling is important for statistical applications except ________. (Points : 1)

the outcomes are more readily understood and therefore really usable

solving using mathematics alone may be very difficult if not impossible

the outcome variables are complicated functions of several input random variables

sampling experiments can be used to better understand important statistics theories

Question 7.7. For a sample size of 12, the degrees of freedom are ________. (Points : 1)

13

144

11

3.46

Question 8.8. A quality assurance technician has checked fifteen 2-liter bottles of a soft drink finding a 99% confidence interval of 1950 ml to 2025 ml for the mean fill volume. Which of the following is true? (Points : 1)

The sample indicates that the population mean lies between 1950 and 2025 ml.

There is a 99% likelihood that the bottles are being under-filled so the bottling process should be stopped.

The technician should recalculate at a 95% confidence interval.

The sample indicates that the sample mean lies closer to 2 liters than not.

Question 9.9. Regarding the standard error of the mean, ________. (Points : 1)

as the sample size increases, the standard error increases

as the sample size decreases, the standard error decreases

as the sample size increases, the standard error decreases

it is defined as one-half of the population standard deviation

Question 10.10. A point estimate is used ________. (Points : 1)

because it's easier to use all the values in the data set than a single value

to estimate the value of a population estimate

when the population parameter is known

only when the population proportion is not known

Question 11.11. Find the standard error of the mean when the population standard deviation is 2.4 and a sample of size 36 is taken. (Points : 1)

4.03

0.6

14.4

0.4

Question 13.13. The standard error of the mean is ________. (Points : 1)

the variance of the sampling distribution of the mean

the standard deviation of the sampling distribution of the mean

the range of the sampling distribution of the mean

the mean of the sampling distribution of the standard deviations

Question 15.15. Find the confidence interval for a population mean of 1.6 pounds at a 95% level of confidence with a sample size of 112 and standard deviation of 0.2 pounds. (Points : 1)

1.89 to 1.90 pounds

4.52 to 42.52 pounds

1.56 to 1.64 pounds

1.72 to 2.08 pounds

Question 16.16. Which of the following is a subjective sampling method? (Points : 1)

cluster sampling

judgment sampling

systematic sampling

stratified sampling

Question 17.17. The margin of error used in a confidence interval is found by ________. (Points : 1)

multiplying the standard error by zα/2

multiplying the population standard deviation and the sample size

dividing the population standard deviation by the sample

multiplying the level of confidence and the standard error

18. A sample mean of 4.56 ounces was just measured from a population of which the population mean is not known. What value should be used for the population mean? (Points : 1)

2.125 ounces

none, since the population mean cannot be estimated

4.56 ounces

the average of all the sample means

189 to 1190 acres

608.84 to 621.16 acres

452 to 4252 acres

172 to 2008 acres

Question 2.2. Which of the following distributions is most likely to approach a normal distribution? (Points : 1)

distribution of all possible sample means of sample size 90

distribution of all possible sample means of sample size 60

distribution of all possible sample means of sample size 120

distribution of all possible sample means of sample size 30

Question 3 A sample was taken of computation errors on an exam: 4, 7, 3, 8, 4, 4, 6, 1, 5, 2, 4, 8, 5, 4, 5. What value should be used for the population standard deviation? (Points : 1)

0.51

1.99

none, since the population standard deviation should never be estimated

1.92

Question 5.5. Confidence interval estimates of a population parameter ________. (Points : 1)

provide a range of values within which the true value of the parameter is believed to be

specify a value that accurately predicts the population parameter

eliminates the effect of sampling error

are used solely to estimate the value of population variance

Question 6.6. All of the following are reasons why random sampling is important for statistical applications except ________. (Points : 1)

the outcomes are more readily understood and therefore really usable

solving using mathematics alone may be very difficult if not impossible

the outcome variables are complicated functions of several input random variables

sampling experiments can be used to better understand important statistics theories

Question 7.7. For a sample size of 12, the degrees of freedom are ________. (Points : 1)

13

144

11

3.46

Question 8.8. A quality assurance technician has checked fifteen 2-liter bottles of a soft drink finding a 99% confidence interval of 1950 ml to 2025 ml for the mean fill volume. Which of the following is true? (Points : 1)

The sample indicates that the population mean lies between 1950 and 2025 ml.

There is a 99% likelihood that the bottles are being under-filled so the bottling process should be stopped.

The technician should recalculate at a 95% confidence interval.

The sample indicates that the sample mean lies closer to 2 liters than not.

Question 9.9. Regarding the standard error of the mean, ________. (Points : 1)

as the sample size increases, the standard error increases

as the sample size decreases, the standard error decreases

as the sample size increases, the standard error decreases

it is defined as one-half of the population standard deviation

Question 10.10. A point estimate is used ________. (Points : 1)

because it's easier to use all the values in the data set than a single value

to estimate the value of a population estimate

when the population parameter is known

only when the population proportion is not known

Question 11.11. Find the standard error of the mean when the population standard deviation is 2.4 and a sample of size 36 is taken. (Points : 1)

4.03

0.6

14.4

0.4

Question 13.13. The standard error of the mean is ________. (Points : 1)

the variance of the sampling distribution of the mean

the standard deviation of the sampling distribution of the mean

the range of the sampling distribution of the mean

the mean of the sampling distribution of the standard deviations

Question 15.15. Find the confidence interval for a population mean of 1.6 pounds at a 95% level of confidence with a sample size of 112 and standard deviation of 0.2 pounds. (Points : 1)

1.89 to 1.90 pounds

4.52 to 42.52 pounds

1.56 to 1.64 pounds

1.72 to 2.08 pounds

Question 16.16. Which of the following is a subjective sampling method? (Points : 1)

cluster sampling

judgment sampling

systematic sampling

stratified sampling

Question 17.17. The margin of error used in a confidence interval is found by ________. (Points : 1)

multiplying the standard error by zα/2

multiplying the population standard deviation and the sample size

dividing the population standard deviation by the sample

multiplying the level of confidence and the standard error

18. A sample mean of 4.56 ounces was just measured from a population of which the population mean is not known. What value should be used for the population mean? (Points : 1)

2.125 ounces

none, since the population mean cannot be estimated

4.56 ounces

the average of all the sample means

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