Deck 8: Statistical Inference: Estimation for Single Populations

Question 1

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

Answer 1

C

Question 2

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.

Answer 2

True

Question 3

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

Answer 3

D

Question 4

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

Question 5

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 6

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

Question 7

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 8

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

Question 11

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

Question 12

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. 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 13

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

Question 14

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.

Question 15

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 16

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 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 meanµ of the population and the confidence level.

Question 19

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

Question 20

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

Question 21

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 22

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 this data,a 90% confidence interval to estimate the population mean can be computed as _______.

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 23

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 24

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) 2.00 to 2.41
C) 2.08 to 2.34
D) 1.93 to 2.49
E) 2.49 to 2.67

Question 25

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 26

A researcher is interested in estimating the mean weight of a semi tracker 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 tracker 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 27

Suppose a researcher is interested in understanding the variation in the price of store brand milk.A random sample of 36 grocery stores 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 28

Suppose a researcher is interested in understanding the variation in the price of store brand milk.A random sample of 36 grocery stores 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 29

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 30

James Desreumaux,VP of Human Resources of American First Banks (AFB),is reviewing the employee training programs of AFB banks. 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 31

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 32

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 33

James Desreumaux,VP of Human Resources of American First Banks (AFB),is reviewing the employee training programs of AFB banks. 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 34

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 35

Suppose a researcher is interested in understanding the variation in the price of store brand milk.A random sample of 36 grocery stores 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 36

A researcher is interested in estimating the mean weight of a semi tracker 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 37

James Desreumaux,VP of Human Resources of American First Banks (AFB),is reviewing the employee training programs of AFB banks. 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) 24.23 to 25.78
C) 24.42 to 25.59
D) 19.15 to 30.85
E) 21.00 t0 32.00

Question 38

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 39

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 this data,a 95% confidence interval to estimate the population mean can be computed as _______.

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 40

The normal distribution is used to test about 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 41

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 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 42

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 43

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 44

James Desreumaux,VP of Human Resources of American First Banks (AFB),is reviewing the employee training programs of AFB banks. 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 45

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 46

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 47

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 48

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 49

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 50

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 51

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) 0.37 to 0.43
D) 0.39 to 0.41
E) 0.40 to 0.45

Question 52

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 53

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 54

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 55

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 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

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 57

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 58

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 59

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 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 60

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 61

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 62

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

A) 645.4458 $\le$ $\sigma$ ² $\le$ 1923.0986
B) 599.3635 $\le$ $\sigma$ ² $\le$ 2135.3859
C) 592.2258 $\le$ $\sigma$ ² $\le$ 2184.4685
D) 652.0129 $\le$ $\sigma$ ² $\le$ 1887.4185
E) 642.0929 $\le$ $\sigma$ ² $\le$ 3982.2989

Question 63

James Desreumaux,VP of Human Resources of American First Banks (AFB),is reviewing the employee training programs of AFB banks. 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 83.33
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 64

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 65

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 66

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 67

The employees of Cybertronics Inc.need to complete a certification online.A random sample of 49 employees gives an average time for completion of all the coursework and passing the tests of 6 hours.Assume that the population standard deviation is 6 hours and the population of employees is fairly large.Construct a 95% confidence interval for the average time required to complete the certification.

A) 18.28 to 21.72
B) 18.32 to 21.68
C) 18.36 to 21.64
D) 18.40 to 21.60
E) 19.76 to 20.24

Question 68

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 $\le$ 189.7279
E) 14.2929 $\le$ $\sigma$ ² $\le$ 139.2989

Question 69

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) 7.3 to 36.9
C) 19.63 to 23.91
D) 19.85 to 23.69
E) 2.69 to 5.1

Question 70

An insurance company is interested in conducting a study to 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 size of sample should be at least _______.

A) 1036
B) 160
C) 41
D) 259
E) 289

Question 71

A study is going to be conducted in which a mean of a lifetime of batteries produced by a certain method will be estimated using a 90% confidence interval.The estimate needs to be within +/- 2 hours of the actual population mean.The population standard deviation is estimated to be around 25.The necessary sample size should be at least _______.

A) 100
B) 21
C) 923
D) 35
E) 423

Question 72

The employees of Cybertronics Inc.need to complete a certification online.A random sample of 16 employees gives an average time for completion of all the coursework and passing the tests of 20 hours.The population standard deviation is unknown but the sample standard deviation is 6 hours.You can assume that the population of employees is fairly large.Construct a 95% confidence interval for the average time required to complete the certification.

A) 17.06 to 22.94
B) 17.37 to 22.63
C) 17.68 to 22.32
D) 17.99 to 22.01
E) 18.31 to 21.69

Question 73

The t score (or table value for Student's t distribution)associated with the upper 5% and 48 degrees of freedom is ______.

A) 1.677
B) 1.687
C) 1.697
D) 1.707
E) 1.717

Question 74

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

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 necessary sample size is at least _______.

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

Question 76

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 77

A researcher wants to estimate the percent of the population that uses the internet to stay informed on world news issues.The researcher wants to estimate the population proportion with a 98% level of confidence. He estimates from previous studies that at least 65% of the population stay informed on world issues through the internet..He also wants the error to be no more than .03.The sample size should be at least _______.

A) 41
B) 313
C) 1677
D) 1373
E) 1500

Question 78

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 _______ e-mail messages.

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

Question 79

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 80

The z value associated with a two-sided 99% confidence interval is _______.

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