Deck 8: Statistical Inference: Estimation for Single Populations

Question 1

A market researcher computed a confidence interval for a population proportion using a 95% confidence level.Her boss decided that she wanted a 99% confidence level instead.The new interval with 99% confidence level will be wider than the original one with a 95% confidence level.

Answer 1

True

Question 2

If the population is normal and its standard deviation, σ, is known and the sample size, n, is large (n ≥ 30), interval estimates for the population mean must be determined using z-values.

Answer 2

True

Question 3

In determining the interval estimates for a population proportion using the sample proportion, it is appropriate to use the z-distribution.

Answer 3

True

Question 4

If the population is not normal but its standard deviation, σ is known and the sample size, n is large (n ≥ 30), z-distribution values may be used to determine interval estimates for the population mean.

Question 5

A t-distribution is similar to a normal distribution, but with flatter tails.

Question 6

In determining the interval estimates for a population variance using the sample variance, it is appropriate to use the values from a chi-square distribution rather than a t-distribution.

Question 7

If the degrees of freedom in a t distribution increase, the difference between the t values and the z values will also increase.

Question 8

When the population standard deviation, σ, is unknown the sample standard deviation, s, is used in determining the interval estimate for the population mean.

Question 9

Use of the chi-square statistic to estimate the population variance is extremely robust to the assumption that the population is normally distributed.

Question 10

In order to find values in the t distribution table, you must determine the appropriate degrees of freedom based on the sample sizes.

Question 11

If the population is normal and its standard deviation, σ, is known but the sample size is small, z-distribution values may not be used to determine interval estimates for the population mean.

Question 12

When a statistic calculated from sample data is used to estimate a population parameter, it is called a point estimate.

Question 13

An assumption underlying the use of t-statistic in sample-based estimation is that the population is normally distributed.

Question 14

Suppose a random sample of 16 is selected from a population with a normal distribution with a known population standard deviation σ of 10.Assume that the sample mean is 4.2.Based on a 90% confidence interval for the population mean, we can conclude that 0.1 is a plausible number for the population mean μ.

Question 15

Catherine Chao, Director of Marketing Research, is evaluating consumer acceptance of a new toothpaste package.Her staff reports that 17% of a random sample of 200 households prefers the new package to all other package designs.If Catherine concludes that 17% of all households prefer the new package, she is using _______.

A)a point estimate
B)a range estimate
C)a statistical parameter
D)an interval estimate
E)an exact estimate

Question 16

Like a t-distribution, a chi-square distribution is symmetrical and extends from minus infinity to plus infinity.

Question 17

When a range of values is used to estimate a population parameter, it is called a range estimate.

Question 18

Given the error we are willing to tolerate, the sample size is determined by the mean, µ of the population and the confidence level.

Question 19

You are thinking of using a t-table to find a 95 percent confidence interval for the mean μ of a population.The distribution of the population is normal and the population standard deviation is unknown.A random sample of size n is drawn from this population.You may use the t-distribution only if the sample size n is small.

Question 20

In estimating the sample size necessary to estimate a population mean, the error of estimation, E, is equal to the difference between the sample mean and the sample standard deviation.

Question 21

Brian Vanecek, VP of Operations at Portland Trust Bank, is evaluating the service level provided to walk-in customers.Accordingly, his staff recorded the waiting times for 64 randomly selected walk-in customers and determined that their mean waiting time was 15 minutes.Assume that the population standard deviation is 4 minutes.The 90% confidence interval for the population mean of waiting times is ________.

A)14.27 to 15.73
B)14.18 to 15.82
C)9.88 to 20.12
D)13.86 to 16.14
E)18.12 to 19.87

Question 22

The table t value associated with the upper 5% of the t distribution and 14 degrees of freedom is _______.

A)2.977
B)2.624
C)2.145
D)1.761
E)1.345

Question 23

James Desreumaux, VP of Human Resources of American First Banks (AFB), is reviewing the employee training programs of AFB.His staff randomly selected personnel files for 100 tellers in the southeast region and determined that their mean training time was 25 hours.Assume that the population standard deviation is 5 hours.The 88% confidence interval for the population mean of training times is ________.

A)17.25 to 32.75
B)24.22 to 25.78
C)24.42 to 25.59
D)19.15 to 30.85
E)21.00 t0 32.00

Question 24

The z value associated with a two-sided 95% confidence interval is _______.

A)1.28
B)1.645
C)1.96
D)2.575
E)2.33

Question 25

A random sample of 64 items is selected from a population of 400 items.The sample mean is 200.The population standard deviation is 48.From these data, the 95% confidence interval to estimate the population mean would be _______.

A)189.21 to 210.79
B)188.24 to 211.76
C)190.13 to 209.87
D)190.94 to 209.06
E)193.45 to 211.09

Question 26

Suppose a researcher is interested in understanding the variation in the price of store brand milk.A random sample of 36 grocery stores is selected from a population and the mean price of store brand milk is calculated.The sample mean is $3.13 with a standard deviation of $0.23.Construct a 95% confidence interval to estimate the population mean.

A)$3.03 to $3.23
B)$3.12 to $3.14
C)$3.05 to $3.21
D)$2.90 to $3.36
E)$3.06 to $3.20

Question 27

The z-distribution is used to estimate a population mean for large samples if the population standard deviation is known."Large" is usually defined as _______.

A)at least 10
B)at least 5% of the population size
C)at least 30
D)at least 12
E)at least 100

Question 28

The z value associated with a two-sided 80% confidence interval is _______.

A)1.645
B)1.28
C)0.84
D)0.29
E)2.00

Question 29

James Desreumaux, VP of Human Resources of American First Banks (AFB), is reviewing the employee training programs of AFB.His staff randomly selected personnel files for 100 tellers in the southeast region and determined that their mean training time was 25 hours.Assume that the population standard deviation is 5 hours.The 92% confidence interval for the population mean of training times is ________.

A)16.25 to 33.75
B)24.30 to 25.71
C)17.95 to 32.05
D)24.12 to 25.88
E)24.45 to 27.32

Question 30

Suppose a researcher is interested in understanding the variation in the price of store brand milk.A random sample of 36 grocery stores is selected from a population and the mean price of store brand milk is calculated.The sample mean is $3.13 with a standard deviation of $0.23.Construct a 92% confidence interval to estimate the population mean.

A)$3.03 to $3.23
B)$3.12 to $3.14
C)$3.05 to $3.21
D)$2.90 to $3.36
E)$3.06 to $3.20

Question 31

Brian Vanecek, VP of Operations at Portland Trust Bank, is evaluating the service level provided to walk-in customers.Accordingly, his staff recorded the waiting times for 64 randomly selected walk-in customers and determined that their mean waiting time was 15 minutes.Assume that the population standard deviation is 4 minutes.The 95% confidence interval for the population mean of waiting times is ________.

A)14.02 to 15.98
B)7.16 to 22.84
C)14.06 to 15.94
D)8.42 to 21.58
E)19.80 to 23.65

Question 32

The z value associated with a two-sided 88% confidence interval is _______.

A)1.28
B)1.55
C)1.17
D)0.88
E)1.90

Question 33

The table t value associated with the upper 5% of the t distribution and 12 degrees of freedom is _______.

A)2.179
B)1.782
C)1.356
D)3.055
E)3.330

Question 34

The z value associated with a two-sided 90% confidence interval is _______.

A)1.28
B)1.645
C)1.96
D)2.575
E)2.33

Question 35

Eugene Gates, Marketing Director of Mansfield Motors Manufacturers, Inc.'s Electrical Division, is leading a study to assess the relative importance of product features.An item on a survey questionnaire distributed to 100 of Mansfield's customers asked them to rate the importance of "ease of maintenance" on a scale of 1 to 10 (with 1 meaning "not important" and 10 meaning "highly important").His staff assembled the following statistics. $$\begin{array} { | l | l l | } \hline & \text { Ea5e of Maintenance } \\\hline \text { Mean } & & 7.5 \\\hline \text { Standard Deviation } && 1.5 \\\hline\end{array}$$ If Eugene concludes that the average rate of "ease of maintenance" for all customers is 7.5, he is using ________.

A)a range estimate
B)a statistical parameter
C)a point estimate
D)an interval estimate
E)a guesstimate

Question 36

Suppose a researcher is interested in understanding the variation in the price of store brand milk.A random sample of 36 grocery stores is selected from a population and the mean price of store brand milk is calculated.The sample mean is $3.13 with a standard deviation of $0.23.Construct a 99% confidence interval to estimate the population mean.

A)$3.03 to $3.23
B)$3.12 to $3.14
C)$3.05 to $3.21
D)$2.90 to $3.36
E)$3.06 to $3.20

Question 37

A random sample of 64 items is selected from a population of 400 items.The sample mean is 200.The population standard deviation is 48.From these data, the 90% confidence interval to estimate the population mean would be _______.

A)189.21 to 210.79
B)188.24 to 211.76
C)190.13 to 209.87
D)190.94 to 209.06
E)193.45 to 211.09

Question 38

James Desreumaux, VP of Human Resources of American First Banks (AFB), is reviewing the employee training programs of AFB.His staff randomly selected personnel files for 100 tellers in the southeast region and determined that their mean training time was 25 hours.Assume that the population standard deviation is 5 hours.The 95% confidence interval for the population mean of training times is ________.

A)15.20 to 34.80
B)24.18 to 25.82
C)24.02 to 25.98
D)16.78 to 33.23
E)23.32 to 35.46

Question 39

Brian Vanecek, VP of Operations at Portland Trust Bank, is evaluating the service level provided to walk-in customers.Accordingly, his staff recorded the waiting times for 45 randomly selected walk-in customers, and calculated that their mean waiting time was 15 minutes.If Brian concludes that the average waiting time for all walk-in customers is 15 minutes, he is using a ________.

A)a range estimate
B)a statistical parameter
C)an interval estimate
D)a point estimate
E)an exact estimate

Question 40

If the standard deviation, σ is known the z-distribution values may not be used to determine interval estimates for the population mean when

A)n<30
B)the distribution is not normal
C)the distribution is skewed
D)n is big
E)n is small (<30)and the distribution is not normal

Question 41

The weights of aluminum castings produced by a process are normally distributed.A random sample of 5 castings is selected; the sample mean weight is 2.21 pounds; and the sample standard deviation is 0.12 pound.The 98% confidence interval for the population mean casting weight is _________.

A)1.76 to 2.66
B)2.01 to 2.41
C)2.08 to 2.34
D)1.93 to 2.49
E)2.49 to 2.67

Question 42

Catherine Chao, Director of Marketing Research, is evaluating consumer acceptance of a new toothpaste package.She randomly selects a sample of 200 households.Forty households prefer the new package to all other package designs.The point estimate for this population proportion is _______.

A)0.20
B)0.25
C)0.40
D)0.45
E)0.55

Question 43

Elwin Osbourne, CIO at GFS, Inc., is studying employee use of GFS e-mail for non-business communications.A random sample of 200 e-mail messages was selected.Thirty of the messages were not business related.The 98% confidence interval for the population proportion is _________.

A)0.108 to 0.192
B)0.153 to 0.247
C)0.091 to 0.209
D)0.145 to 0.255
E)0.250 to 0.275

Question 44

Life tests performed on a sample of 13 batteries of a new model indicated: (1)an average life of 75 months, and (2)a standard deviation of 5 months.Other battery models, produced by similar processes, have normally distributed life spans.The 98% confidence interval for the population mean life of the new model is _________.

A)63.37 to 86.63
B)61.60 to 88.41
C)71.77 to 78.23
D)71.28 to 78.72
E)79.86 to 81.28

Question 45

A researcher wants to estimate the proportion of the population which possesses a given characteristic.A random sample of size 1800 is taken resulting in 450 items which possess the characteristic.The point estimate for this population proportion is _______.

A)0.55
B)0.45
C)0.35
D)0.25
E)0.15

Question 46

The table t value associated with the upper 10% of the t distribution and 23 degrees of freedom is _______.

A)1.319
B)1.714
C)2.069
D)1.321
E)2.332

Question 47

A researcher is interested in estimating the mean weight of a semi tractor truck to determine the potential load capacity.She takes a random sample of 17 trucks and computes a sample mean of 20,000 pounds with sample standard deviation of 1,500.She decides to construct a 98% confidence interval to estimate the mean.The degrees of freedom associated with this problem are _______.

A)18
B)17
C)16
D)15
E)20

Question 48

A random sample of 225 items from a population results in 60% possessing a given characteristic.Using this information, the researcher constructs a 90% confidence interval to estimate the population proportion.The resulting confidence interval is _______.

A)0.546 to 0.654
B)0.536 to 0.664
C)0.596 to 0.604
D)0.571 to 0.629
E)0.629 to 0.687

Question 49

A large national company is considering negotiating cellular phone rates for its employees.The Human Resource department would like to estimate the proportion of its employee population who own an Apple iPhone.A random sample of size 250 is taken and 40% of the sample own and iPhone.The 90% confidence interval to estimate the population proportion is ____.

A)0.35 to 0.45
B)0.34 to 0.46
C)0.38 to 0.42
D)0.39 to 0.41
E)0.40 to 0.45

Question 50

A researcher is interested in estimating the mean weight of a semi tractor truck to determine the potential load capacity.She takes a random sample of 17 trucks and computes a sample mean of 20,000 pounds with sample standard deviation of 1,500.The 95% confidence interval for the population mean weight of a semi tractor truck is ______________.

A)19,232 to 20,768
B)19,365 to 20,635
C)19,229 to 20,771
D)19,367 to 20,633
E)119.89 to 122.12 18,500 to 21,500

Question 51

Elwin Osbourne, CIO at GFS, Inc., is studying employee use of GFS e-mail for non-business communications.A random sample of 200 e-mail messages was selected.Thirty of the messages were not business related.The point estimate for this population proportion is _______.

A)0.150
B)0.300
C)0.182
D)0.667
E)0.786

Question 52

Elwin Osbourne, CIO at GFS, Inc., is studying employee use of GFS e-mail for non-business communications.A random sample of 200 e-mail messages was selected.Thirty of the messages were not business related.The 95% confidence interval for the population proportion is _________.

A)0.108 to 0.192
B)0.153 to 0.247
C)0.091 to 0.209
D)0.101 to 0.199
E)0.199 to 0.201

Question 53

A large trucking company wants to estimate the proportion of its tracker truck population with refrigerated carrier capacity.A random sample of 200 tracker trucks is taken and 30% of the sample have refrigerated carrier capacity.The 90% confidence interval to estimate the population proportion is _______.

A)0.53 to 0.67
B)0.25 to 0.35
C)0.24 to 0.36
D)0.27 to 0.33
E)0.33 to 0.39

Question 54

A large national company is considering negotiating cellular phone rates for its employees.The Human Resource department would like to estimate the proportion of its employee population who own an Apple iPhone.A random sample of size 250 is taken and 40% of the sample own and iPhone.The 95% confidence interval to estimate the population proportion is _______.

A)0.35 to 0.45
B)0.34 to 0.46
C)0.37 to 0.43
D)0.39 to 0.41
E)0.40 to 0.42

Question 55

A large trucking company wants to estimate the proportion of its tractor truck population with refrigerated carrier capacity.A random sample of 200 tractor trucks is taken and 30% of the sample have refrigerated carrier capacity.The 95% confidence interval to estimate the population proportion is _______.

A)0.53 to 0.67
B)0.25 to 0.35
C)0.24 to 0.36
D)0.27 to 0.33
E)0.28 to 0.34

Question 56

Life tests performed on a sample of 13 batteries of a new model indicated: (1)an average life of 75 months, and (2)a standard deviation of 5 months.Other battery models, produced by similar processes, have normally distributed life spans.The 90% confidence interval for the population mean life of the new model is _________.

A)66.78 to 83.23
B)72.72 to 77.28
C)72.53 to 77.47
D)66.09 to 83.91
E)73.34 to 76.25

Question 57

A random sample of 225 items from a population results in 60% possessing a given characteristic.Using this information, the researcher constructs a 99% confidence interval to estimate the population proportion.The resulting confidence interval is _______.

A)0.54 to 0.66
B)0.59 to 0.61
C)0.57 to 0.63
D)0.52 to 0.68
E)0.68 to 0.76

Question 58

A researcher is interested in estimating the mean weight of a semi tractor truck to determine the potential load capacity.She takes a random sample of 17 trucks and computes a sample mean of 20,000 pounds with sample standard deviation of 1,500.The 90% confidence interval for the population mean weight of a semi tractor truck is ______________.

A)19,365 to 20,635
B)19,367 to 20,633
C)19,514 to 20,486
D)19,515 to 20,485
E)18,500 to 21,500

Question 59

A researcher wants to estimate the proportion of the population which possesses a given characteristic.A random sample of size 800 is taken resulting in 360 items which possess the characteristic.The point estimate for this population proportion is _______.

A)0.55
B)0.45
C)0.35
D)0.65
E)0.70

Question 60

Elwin Osbourne, CIO at GFS, Inc., is studying employee use of GFS e-mail for non-business communications.A random sample of 200 e-mail messages was selected.Thirty of the messages were not business related.The 90% confidence interval for the population proportion is _________.

A)0.108 to 0.192
B)0.153 to 0.247
C)0.091 to 0.209
D)0.145 to 0.255
E)0.255 to 0.265

Question 61

A study is going to be conducted in which a population mean will be estimated using a 92% confidence interval.The estimate needs to be within 12 of the actual population mean.The population variance is estimated to be around 2500.The necessary sample size should be at least _______.

A)15
B)47
C)54
D)638
E)700

Question 62

Given n = 17, s² = 18.56, and that the population is normally distributed, the 80% confidence interval for the population variance is ________.

A)11.4372 $\le$ $\sigma$ ² $\le$ 36.3848
B)23.5418 $\le$ $\sigma$ ² $\le$ 9.31223
C)12.6141 $\le$ $\sigma$ ² $\le$ 31.8892
D)11.2929 $\le$ $\sigma$ ² $\le$ 37.2989
E)14.2929 $\le$$\sigma$ ² $\le$ 39.2989

Question 63

Brian Vanecek, VP of Operations at Portland Trust Bank, is evaluating the service level provided to walk-in customers.Brian would like to minimize the variance of waiting time for these customers, since this would mean each customer received the same level of service.Accordingly, his staff recorded the waiting times for 15 randomly selected walk-in customers, and determined that their mean waiting time was 15 minutes and that the standard deviation was 4 minutes.Assume that waiting time is normally distributed.The 90% confidence interval for the population variance of waiting times is ________.

A)9.46 to 34.09
B)56.25 to 64.87
C)11.05 to 16.03
D)8.58 to 39.79
E)12.50 to 42.35

Question 64

James Desreumaux, VP of Human Resources of American First Banks (AFB), is reviewing the employee training programs of AFB.His staff randomly selected personnel files for 10 tellers in the southwest region, and determined that their mean training time was 25 hours and that the standard deviation was 5 hours.Assume that training times are normally distributed.The 90% confidence interval for the population variance of training times is ________.

A)11.83 to 83.33
B)2.37 to 16.67
C)2.66 to 13.51
D)13.30 to 67.67
E)15.00 to 68.00

Question 65

Elwin Osbourne, CIO at GFS, Inc., is studying employee use of GFS e-mail for non-business communications.He plans to use a 95% confidence interval estimate of the proportion of e-mail messages that are non-business; he will accept a 0.05 error.Previous studies indicate that approximately 30% of employee e-mail is not business related.Elwin should sample _______ e-mail messages.

A)323
B)12
C)457
D)14
E)100

Question 66

An insurance company is interested in conducting a study to estimate the population proportion of teenagers who obtain a driving permit within 1 year of their 16^th birthday.A level of confidence of 99% will be used and an error of no more than .04 is desired.There is no knowledge as to what the population proportion will be.The approximate sample size should be at least _______.

A)1037
B)160
C)41
D)259
E)289

Question 67

Elwin Osbourne, CIO at GFS, Inc., is studying employee use of GFS e-mail for non-business communications.He plans to use a 98% confidence interval estimate of the proportion of e-mail messages that are non-business; he will accept a 0.05 error.Previous studies indicate that approximately 30% of employee e-mail is not business related.Elwin should sample approximately _______ e-mail messages.

A)323
B)12
C)456
D)14
E)100

Question 68

A researcher wants to estimate the percent of the population that uses the radio to stay informed on local news issues.The researcher wants to estimate the population proportion with a 95% level of confidence.He estimates from previous studies that no more than 30% of the population stay informed on local issues through the radio.The researcher wants the estimate to have an error of no more than .03.The necessary sample size is at least _______.

A)27
B)188
C)211
D)897
E)900

Question 69

Given n = 20, s = 32, and that the population is normally distributed, the 90% confidence interval for the population variance is ________.

A)645.45 $\le$ $\sigma$ ² $\le$ 1923.10
B)599.36 $\le$ $\sigma$ ² $\le$ 2135.39
C)592.23 $\le$ $\sigma$ ² $\le$ 2184.47
D)652.01 $\le$ $\sigma$ ² $\le$ 1887.42
E)642.09 $\le$ $\sigma$ ² $\le$ 3982.30

Question 70

Catherine Chao, Director of Marketing Research, is evaluating consumer acceptance of a new toothpaste package.She randomly selects a sample of 200 households.Forty households prefer the new package to all other package designs.The 90% confidence interval for the population proportion is _________.

A)0.199 to 0.201
B)0.153 to 0.247
C)0.164 to 0.236
D)0.145 to 0.255
E)0.185 to 0.275

Question 71

James Desreumaux, VP of Human Resources of American First Banks (AFB), is reviewing the employee training programs of AFB.His staff randomly selected personnel files for 10 tellers in the southwest region, and determined that their mean training time was 25 hours and that the standard deviation was 5 hours.Assume that training times are normally distributed.The 95% confidence interval for the population variance of training times is ________.

A)11.83 to 83.32
B)2.37 to 16.67
C)2.66 to 13.51
D)13.30 to 67.57
E)15.40 to 68.28

Question 72

Velma Vasquez, fund manager of the Vasquez Value Fund, manages a portfolio of 250 common stocks.Velma relies on various statistics, such as variance, to assess the overall risk of stocks in an economic sector.Her staff reported that for a sample 14 utility stocks the mean annualized return was 14% and that the variance was 3%.Assume that annualized returns are normally distributed.The 90% confidence interval for the population variance of annualized returns for utility stocks is _______.

A)0.018 to 0.064
B)0.016 to 0.078
C)0.017 to 0.066
D)0.016 to 0.075
E)0.020 to 0.080

Question 73

Suppose the fat content of a hotdog follows normal distribution.Ten random measurements give a mean of 21.77 and standard deviation of 3.69.The 90% confidence interval for the population variance of fat content of a hotdog is ________

A)5.2 to 21.3
B)7.2 to 36.9
C)19.63 to 23.91
D)19.85 to 23.69
E)2.69 to 5.1

Question 74

Given n = 12, s² = 44.90, and that the population is normally distributed, the 99% confidence interval for the population variance is ________.

A)19.0391 $\le$$\sigma$ ² $\le$ 175.2888
B)23.0881 $\le$ $\sigma$ ² $\le$ 122.3495
C)25.6253 $\le$ $\sigma$ ² $\le$ 103.0993
D)18.4588 $\le$ $\sigma$ ² $\le$ 189.7264
E)14.2929 $\le$ $\sigma$ ² $\le$ 139.2989

Question 75

A researcher wants to estimate the percent of the population that uses the radio to stay informed on local news issues.The researcher wants to estimate the population proportion with a 90% level of confidence.He estimates from previous studies that no more than 30% of the population stay informed on local issues through the radio.The researcher wants the estimate to have an error of no more than .02.The approximate sample size is at least _______.

A)29
B)47
C)298
D)1421
E)1500

Question 76

Catherine Chao, Director of Marketing Research, is evaluating consumer acceptance of a new toothpaste package.She plans to use a 95% confidence interval estimate of the proportion of households which prefer the new packages; she will accept a 0.05 error.Previous studies indicate that new packaging has an approximately 70% acceptance rate.The sample size should be at least _______.

A)27
B)59
C)323
D)427
E)500

Question 77

Brian Vanecek, VP of Operations at Portland Trust Bank, is evaluating the service level provided to walk-in customers.Brian would like to minimize the variance of waiting time for these customers, since this would mean each customer received the same level of service.Accordingly, his staff recorded the waiting times for 15 randomly selected walk-in customers, and determined that their mean waiting time was 15 minutes and that the standard deviation was 4 minutes.Assume that waiting time is normally distributed.The 95% confidence interval for the population variance of waiting times is ________.

A)9.46 to 34.09
B)56.25 to 64.87
C)11.05 to 16.03
D)8.58 to 39.79
E)12.50 to 42.35

Question 78

Velma Vasquez, fund manager of the Vasquez Value Fund, manages a portfolio of 250 common stocks.Velma relies on various statistics, such as variance, to assess the overall risk of stocks in an economic sector.Her staff reported that for a sample 14 utility stocks the mean annualized return was 14% and that the variance was 3%.Assume that annualized returns are normally distributed.The 95% confidence interval for the population variance of annualized returns for utility stocks is _______.

A)0.018 to 0.064
B)0.016 to 0.078
C)0.017 to 0.066
D)0.016 to 0.075
E)0.020 to 0.080

Question 79

A researcher wants to determine the sample size necessary to adequately conduct a study to estimate the population mean to within 5 points.The range of population values is 80 and the researcher plans to use a 90% level of confidence.The sample size should be at least _______.

A)44
B)62
C)216
D)692
E)700

Question 80

In estimating the sample size necessary to estimate p, if there is no good approximation for the value of p available, the value of ____ should be used as an estimate of p in the formula.

A)0.10
B)0.50
C)0.40
D)1.96
E)2.00