Deck 17: Additional Topics in Sampling

Question 1

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
A supermarket chain has 25 stores in the North,30 in the South,50 in the Midwest,and 35 in the West.Using a proportional allocation of a random sample of 30% of the outlets,the manager records the following means and standard deviations.

Quota sampling is an example of a:

A)probabilistic sampling technique.
B)stratified sampling technique.
C)nonprobabilistic sampling technique.
D)cluster sampling technique.

Answer 1

nonprobabilistic sampling technique.

Question 2

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
An auditor is faced with reviewing 1,098 invoices.From a random sample of 134 of these accounts,he found that the average amount was $548 with a standard deviation of $129.He also found that 42 out of the 134 in the sample were from out-of-state suppliers.
Estimate the total dollar value of these invoices.

A)$601,704
B)$721,450
C)$484,566
D)$852,989

Answer 2

$601,704

Question 3

A sales representative has 600 accounts.He wants to take a random sample to determine the mean amount of yearly sales for these accounts.From past research,he knows that the population standard deviation is approximately $28,000.How large a sample should he take in order to estimate the population mean within $8,000 at a 98% level of confidence?

A)60
B)45
C)75
D)30

Answer 3

60

Question 4

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A sales representative has 425 accounts.From a random sample of 60 of these accounts,she found that the average yearly order was $1,250 with a standard deviation of $70.She also found that 28 out of 60 in the sample have placed an order in the last four weeks.
Find a 90% confidence interval for the total amount of sales for the sales representative.

A)$531,250 ± 5,861.93
B)$87,500 ± $3,651.51
C)$75,000 ± $2,840.11
D)$29,750 ± $4,115.33

Question 5

Which of the following sampling methods would be appropriate when the population can conveniently be subdivided into relatively small and geographically compact units?

A)simple random sampling
B)cluster sampling
C)stratified sampling
D)systematic sampling

Question 6

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
A supermarket chain has 25 stores in the North,30 in the South,50 in the Midwest,and 35 in the West.Using a proportional allocation of a random sample of 30% of the outlets,the manager records the following means and standard deviations.

Find a 95% confidence interval for the total sales.

A)19976.60 ± 450.85
B)19976.60 ± 284.21
C)19976.60 ± 729.90
D)19976.60 ± 605.83

Question 7

In which of the following sampling methods are the individuals of a population subdivided into mutually exclusive and collectively exhaustive separate subpopulations with a common characteristic?

A)cluster sampling
B)simple random sampling
C)stratified sampling
D)systematic sampling

Question 8

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
A supermarket chain has 25 stores in the North,30 in the South,50 in the Midwest,and 35 in the West.Using a proportional allocation of a random sample of 30% of the outlets,the manager records the following means and standard deviations.

Estimate the total sales for the corporation based on these estimates.

A)15,484.39
B)19,976.60
C)28,778.85
D)24,848.36

Question 9

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
An auditor is faced with reviewing 1,098 invoices.From a random sample of 134 of these accounts,he found that the average amount was $548 with a standard deviation of $129.He also found that 42 out of the 134 in the sample were from out-of-state suppliers.
Find a 95% confidence interval for the proportion of all invoices that are from out-of-state suppliers.

A)0.313 ± 0.0739
B)0.313 ± 0.1298
C)0.313 ± 0.0426
D)0.313 ± 0.1519

Question 10

For a sample of 145 observations from a population of 744,the sample mean is 22.6 and the sample standard deviation is 3.8.Create a 90% confidence interval for the population mean.

A)22.6 ± 0.113
B)22.6 ± 1.328
C)22.6 ± 0.894
D)22.6 ± 0.466

Question 11

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
A sales representative has 425 accounts.From a random sample of 60 of these accounts,she found that the average yearly order was $1,250 with a standard deviation of $70.She also found that 28 out of 60 in the sample have placed an order in the last four weeks.
A simple random sample of 250 from a total 1,200 colleges in the United States contains 40 colleges that charge a technology fee in addition to the tuition fee.Find a 99% confidence interval for the proportion of all colleges charging a technology fee.

A)0)16 ± 0.087
B)0)16 ± 0.021
C)0)16 ± 0.115
D)0)16 ± 0.053

Question 12

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
An auditor is faced with reviewing 1,098 invoices.From a random sample of 134 of these accounts,he found that the average amount was $548 with a standard deviation of $129.He also found that 42 out of the 134 in the sample were from out-of-state suppliers.
Find a 95% confidence interval for the total dollar value of these invoices.

A)60,1704 ± 10258.15
B)60,1704 ± 8168.36
C)60,1704 ± 15987.64
D)60,1704 ± 22481.79

Question 13

Suppose that for a sample of 65 observations from a population of 500,the sample mean is 25.6 and the sample standard deviation is 2.8.Create a 90% confidence interval for the population mean.

A)25.6 ± 0.318
B)25.6 ± 0.415
C)25.6 ± 0.467
D)25.6 ± 0.533

Question 14

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
A supermarket chain has 25 stores in the North,30 in the South,50 in the Midwest,and 35 in the West.Using a proportional allocation of a random sample of 30% of the outlets,the manager records the following means and standard deviations.

Estimate the population mean.

A)134.38
B)158.31
C)142.69
D)165.44

Question 15

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
A sales representative has 425 accounts.From a random sample of 60 of these accounts,she found that the average yearly order was $1,250 with a standard deviation of $70.She also found that 28 out of 60 in the sample have placed an order in the last four weeks.
Find the 90% confidence interval for the proportion of all accounts that placed an order within the last four weeks.

A)0.467 ± 0.412
B)0.467 ± 0.266
C)0.467 ± 0.838
D)0.467 ± 0.120

Question 16

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
A sales representative has 425 accounts.From a random sample of 60 of these accounts,she found that the average yearly order was $1,250 with a standard deviation of $70.She also found that 28 out of 60 in the sample have placed an order in the last four weeks.
Estimate the total amount of sales for the sales representative.

A)$297,500
B)$750,000
C)$375,640
D)$531,250

Question 17

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
An auditor is faced with reviewing 1,098 invoices.From a random sample of 134 of these accounts,he found that the average amount was $548 with a standard deviation of $129.He also found that 42 out of the 134 in the sample were from out-of-state suppliers.
Estimate the proportion of all invoices that are from out-of-state suppliers.

A)0.649
B)0.584
C)0.313
D)0.258

Question 18

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
A supermarket chain has 25 stores in the North,30 in the South,50 in the Midwest,and 35 in the West.Using a proportional allocation of a random sample of 30% of the outlets,the manager records the following means and standard deviations.

Find a 95% confidence interval for the population mean.

A)142.69 ± 5.22
B)142.69 ± 1.96
C)142.69 ± 2.66
D)142.69 ± 4.58

Question 19

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
A sales representative has 425 accounts.From a random sample of 60 of these accounts,she found that the average yearly order was $1,250 with a standard deviation of $70.She also found that 28 out of 60 in the sample have placed an order in the last four weeks.
Which of the following is an example of a nonprobabilistic sampling technique?

A)simple random sampling
B)stratified random sampling
C)cluster sampling
D)quota sampling

Question 20

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
A sales representative has 425 accounts.From a random sample of 60 of these accounts,she found that the average yearly order was $1,250 with a standard deviation of $70.She also found that 28 out of 60 in the sample have placed an order in the last four weeks.
Estimate the proportion of all accounts that placed an order within the last four weeks.

A)0.683
B)0.218
C)0.467
D)0.356

Question 21

In stratified random sampling,the stratum sample mean is a biased estimator of the population mean.

Question 22

An unbiased estimator of the variance of the estimator of μ follows from the fact that the samples in each stratum are independent of one another.

Question 23

From the unbiased estimation procedure for the variance of the stratum sample mean,the point estimate is given by
=
×

Question 24

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
In a stratified random sample of students on a campus,sample members were asked to rate,on a scale of 1 (poor)to 5 (excellent),opportunities for improving the college infrastructure.The results are shown in the table below.

If a total sample of 150 students is taken,determine the number of freshmen and sophomores under the optimum allocation scheme,assuming that the stratum population standard deviations are the same as the corresponding sample values.

A)89.15
B)71.86
C)38.48
D)60.85

Question 25

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
In a stratified random sample of students on a campus,sample members were asked to rate,on a scale of 1 (poor)to 5 (excellent),opportunities for improving the college infrastructure.The results are shown in the table below.

If a total sample of 150 students is taken,determine the number of juniors and seniors under the optimum allocation scheme,assuming that the stratum population standard deviations are the same as the corresponding sample values.

A)89.15
B)71.86
C)38.48
D)60.85

Question 26

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
In a stratified random sample of students on a campus,sample members were asked to rate,on a scale of 1 (poor)to 5 (excellent),opportunities for improving the college infrastructure.The results are shown in the table below.

If a total sample of 150 students is taken,determine the number of freshmen and sophomores under the proportional allocation scheme.

A)132.45
B)81.38
C)114.86
D)65.21

Question 27

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
The faculty advisor at a local business school is interested in determining the monthly expenditures on stationeries for students.The advisor samples some students from each class and computes the sample mean and standard deviation for each class.

Find a 98% confidence interval for the total expenditures.

A)13,128.01 ± 126.71
B)13,128.01 ± 581.23
C)13,128.01 ± 342.58
D)13,128.01 ± 665.49

Question 28

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
An auditor,examining a total of 650 accounts receivable by a corporation,selected a random sample of 45 accounts.The sample mean is $108.34 and the sample standard deviation is $30.85.
Find a 95% confidence interval for the population mean.

A)108.34 ± 17.45
B)108.34 ± 2.25
C)108.34 ± 8.70
D)108.34 ± 13.76

Question 29

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
In a stratified random sample of students on a campus,sample members were asked to rate,on a scale of 1 (poor)to 5 (excellent),opportunities for improving the college infrastructure.The results are shown in the table below.

An automobile company with 3500 employees needs to take a simple random sample in order to estimate the employee population's average satisfaction level on a scale of 0-100.From previous experience,it is estimated that the population standard deviation is approximately 8.0.A 95 % confidence interval for the population mean must extend 3.0 on each side of the sample mean.How many employees need to be sampled to achieve this objective?

A)28
B)24
C)42
D)32

Question 30

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
The faculty advisor at a local business school is interested in determining the monthly expenditures on stationeries for students.The advisor samples some students from each class and computes the sample mean and standard deviation for each class.

Estimate the total expenditures for the population.

A)22,678.63
B)13,128.01
C)26,288.34
D)18,944.58

Question 31

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
In a stratified random sample of students on a campus,sample members were asked to rate,on a scale of 1 (poor)to 5 (excellent),opportunities for improving the college infrastructure.The results are shown in the table below.

Find a 90% confidence interval for the mean rating given by all juniors and seniors on the campus.

A)4.65 ± 0.369
B)4.65 ± 0.183
C)4.65 ± 0.254
D)4.65 ± 0.513

Question 32

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
In a stratified random sample of students on a campus,sample members were asked to rate,on a scale of 1 (poor)to 5 (excellent),opportunities for improving the college infrastructure.The results are shown in the table below.

Find a 90% confidence interval for the mean rating given by all the undergraduate students on the campus.

A)4.29 ± 0.684
B)4.29 ± 0.421
C)4.29 ± 0.148
D)4.29 ± 0.232

Question 33

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
In a stratified random sample of students on a campus,sample members were asked to rate,on a scale of 1 (poor)to 5 (excellent),opportunities for improving the college infrastructure.The results are shown in the table below.

Find a 90% confidence interval for the mean rating given by all freshmen and sophomores on the campus.

A)3.98 ± 0.592
B)3.98 ± 0.229
C)3.98 ± 0.712
D)3.98 ± 0.456

Question 34

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
The faculty advisor at a local business school is interested in determining the monthly expenditures on stationeries for students.The advisor samples some students from each class and computes the sample mean and standard deviation for each class.

Find a 98% confidence interval for the mean monthly expenditures.

A)64.67 ± 5.285
B)64.67 ± 3.278
C)64.67 ± 7.875
D)64.67 ± 4.326

Question 35

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
The faculty advisor at a local business school is interested in determining the monthly expenditures on stationeries for students.The advisor samples some students from each class and computes the sample mean and standard deviation for each class.

Estimate the mean monthly expenditures.

A)78.26
B)73.74
C)59.82
D)64.67

Question 36

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
An auditor,examining a total of 650 accounts receivable by a corporation,selected a random sample of 45 accounts.The sample mean is $108.34 and the sample standard deviation is $30.85.
Using an unbiased estimation procedure,find an estimate of the variance of the population mean.

A)29.60
B)19.72
C)14.26
D)25.87

Question 37

In order to take a simple random sample from each stratum,each individual member of the population must be identifiable as belonging to one,and only one,of the strata.

Question 38

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
An auditor,examining a total of 650 accounts receivable by a corporation,selected a random sample of 45 accounts.The sample mean is $108.34 and the sample standard deviation is $30.85.
A director of marketing research needs a sample of households to participate in the testing of a new toothpaste package.She directs five members of her staff to find five households each.This is an example of:

A)cluster sampling.
B)stratified sampling.
C)quota sampling.
D)systematic sampling.

Question 39

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
An auditor,examining a total of 650 accounts receivable by a corporation,selected a random sample of 45 accounts.The sample mean is $108.34 and the sample standard deviation is $30.85.
Find a 95% confidence interval for the total amount of the 800 accounts receivable.

A)70,421 ± 3,836.24
B)70,421 ± 4,589.73
C)70,421 ± 2,057.41
D)70,421 ± 5,657.48

Question 40

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
In a stratified random sample of students on a campus,sample members were asked to rate,on a scale of 1 (poor)to 5 (excellent),opportunities for improving the college infrastructure.The results are shown in the table below.

If a total sample of 150 students is taken,determine the number of juniors and seniors under the proportional allocation scheme.

A)51.81
B)36.48
C)42.79
D)68.62

Question 41

In cluster sampling,a complete census is taken for each chosen cluster.

Question 42

The distinction between cluster sampling and stratified sampling is that in the former a random sample of clusters is taken,while in the latter a complete census of stratum members is drawn.

Question 43

The sample size for the j^th stratum using proportional allocation is n_j =
× n.

Question 44

Stratified random sampling is an example of a nonprobabilistic sampling method.

Question 45

The actual total sample size required to achieve a particular value for the variance depends on the manner in which the sample observations are allocated among the strata.

Question 46

Since sample members are geographically close to one another within clusters,their contact by interviewers is relatively expensive.

Question 47

In many practical applications,nonprobabilistic methods are used for selecting sample members,primarily as a matter of convenience.

Question 48

Explain in detail what is meant by "cluster sampling has a superficial resemblance to stratified sampling."

Question 49

Compared with optimal allocation,proportional allocation allocates relatively more sample effort to strata in which the population variance is highest.

Question 50

Stratified random sampling involves selecting a simple random sample from each of a given number of subpopulations,called strata.

Question 51

A smaller sample size is required where greater population variability exists.

Question 52

The use of proportional allocation in stratified sampling implies that the same number of elements is sampled in each stratum.

Question 53

Proportional allocation occurs when the proportion of sample members from any stratum is the same as the proportion of population members in that stratum.

Question 54

If stratified random sampling is employed,the pilot study can be used to provide estimates of the individual stratum variances.

Question 55

For a sample of 75 observations from a population of 573,the sample mean is 33.2 and the sample standard deviation is 3.6.Develop a 95% confidence interval for the population mean.

Question 56

An apartment complex manager randomly selects 10 buildings from the complex's 30 buildings,and then interviews one household member from each apartment in the 10 buildings.This is an example of cluster sampling.

Question 57

The drawback of quota sampling is that,since the sample is not chosen using probabilistic methods,there is no valid way of determining the reliability of the resulting estimates.

Question 58

An unbiased estimation procedure for the variance of the estimator of the overall population mean yields the point estimate
=

.

Question 59

A stratified sampling technique is used when the population can conveniently be subdivided into relatively small and geographically compact units.

Question 60

In stratified random sampling,it is necessary to take the same number of sample members from every stratum.

Question 61

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
The faculty advisor for the marketing society at a local business school is interested in determining the monthly expenditures on entertainment for marketing students.The advisor samples some students from each class and computes the sample mean and standard deviation for each class.

Find a 95% confidence interval for the mean monthly expenditures.

Question 62

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
A corporation has 30 outlets in the North,40 in the South,60 in the Midwest,and 45 in the West.Using a proportional allocation of a random sample of 20% of the outlets,the manager records the following means and standard deviations.

Estimate the total sales for the corporation based on these estimates.

Question 63

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
A corporation has 30 outlets in the North,40 in the South,60 in the Midwest,and 45 in the West.Using a proportional allocation of a random sample of 20% of the outlets,the manager records the following means and standard deviations.

Estimate the population mean.

Question 64

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
A corporation has 30 outlets in the North,40 in the South,60 in the Midwest,and 45 in the West.Using a proportional allocation of a random sample of 20% of the outlets,the manager records the following means and standard deviations.

A sales representative has 850 accounts.She is interested in determining the proportion of her accounts that have placed an order within the past month.For a standard deviation of 0.5,how large a sample should she take in order to estimate the population proportion within five percent at a 95% level of confidence?

Question 65

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
A corporation has 30 outlets in the North,40 in the South,60 in the Midwest,and 45 in the West.Using a proportional allocation of a random sample of 20% of the outlets,the manager records the following means and standard deviations.

Describe two methods of nonprobabilistic sampling methods.Give an example for each.What are the advantages and disadvantages of each?

Question 66

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
A corporation has 30 outlets in the North,40 in the South,60 in the Midwest,and 45 in the West.Using a proportional allocation of a random sample of 20% of the outlets,the manager records the following means and standard deviations.

Find a 99% confidence interval for the population mean.

Question 67

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
An auditor is faced with reviewing 1,294 invoices.From a random sample of 122 of these accounts,she found that the average amount was $639 with a standard deviation of $143.She also found that 37 out of the 122 in the sample were from out-of-state suppliers.
Estimate the proportion of all invoices that are from out-of-state suppliers.

Question 68

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
An auditor is faced with reviewing 1,294 invoices.From a random sample of 122 of these accounts,she found that the average amount was $639 with a standard deviation of $143.She also found that 37 out of the 122 in the sample were from out-of-state suppliers.
Find a 90% confidence interval for the total dollar value of these invoices.

Question 69

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
A corporation has 30 outlets in the North,40 in the South,60 in the Midwest,and 45 in the West.Using a proportional allocation of a random sample of 20% of the outlets,the manager records the following means and standard deviations.

Find a 95% confidence interval for the total sales.

Question 70

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
A sales representative has 398 accounts.From a random sample of 56 of these accounts,she found that the average yearly order was $1,239 with a standard deviation of $73,and that 27 had placed an order within the last 30 days.
Find the 90% confidence interval for the proportion of all accounts that placed an order within the last 30 days.

Question 71

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
The faculty advisor for the marketing society at a local business school is interested in determining the monthly expenditures on entertainment for marketing students.The advisor samples some students from each class and computes the sample mean and standard deviation for each class.

Find a 90% confidence interval for the total expenditures.

Question 72

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
A sales representative has 398 accounts.From a random sample of 56 of these accounts,she found that the average yearly order was $1,239 with a standard deviation of $73,and that 27 had placed an order within the last 30 days.
Estimate the proportion of all accounts that placed an order within the last 30 days.

Question 73

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
A corporation has 30 outlets in the North,40 in the South,60 in the Midwest,and 45 in the West.Using a proportional allocation of a random sample of 20% of the outlets,the manager records the following means and standard deviations.

Compare and contrast stratified sampling and cluster sampling.Under what circumstances would these techniques be chosen over a simple random sample?

Question 74

A sales representative has 798 accounts.She wants to take a random sample to determine the mean amount of yearly sales for these accounts.From past research,she knows that the population standard deviation is approximately $37,000.How large a sample should she take in order to estimate the population mean within $10,000 at a 99% level of confidence?

Question 75

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
An auditor is faced with reviewing 1,294 invoices.From a random sample of 122 of these accounts,she found that the average amount was $639 with a standard deviation of $143.She also found that 37 out of the 122 in the sample were from out-of-state suppliers.
Find a 95% confidence interval for the proportion of all invoices that are from out-of-state suppliers.

Question 76

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
A corporation has 30 outlets in the North,40 in the South,60 in the Midwest,and 45 in the West.Using a proportional allocation of a random sample of 20% of the outlets,the manager records the following means and standard deviations.

For a sample of 126 observations from a population of 873,the sample mean is 17.2 and the sample standard deviation is 2.4.Create a 99% confidence interval for the population mean.

Question 77

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
The faculty advisor for the marketing society at a local business school is interested in determining the monthly expenditures on entertainment for marketing students.The advisor samples some students from each class and computes the sample mean and standard deviation for each class.

Estimate the total expenditures for the population.

Question 78

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
An auditor is faced with reviewing 1,294 invoices.From a random sample of 122 of these accounts,she found that the average amount was $639 with a standard deviation of $143.She also found that 37 out of the 122 in the sample were from out-of-state suppliers.
Estimate the total dollar value of these invoices.

Question 79

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
A corporation has 30 outlets in the North,40 in the South,60 in the Midwest,and 45 in the West.Using a proportional allocation of a random sample of 20% of the outlets,the manager records the following means and standard deviations.

Briefly describe what is meant by "two-phase sampling," and discuss its advantages and disadvantages.

Question 80

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
The faculty advisor for the marketing society at a local business school is interested in determining the monthly expenditures on entertainment for marketing students.The advisor samples some students from each class and computes the sample mean and standard deviation for each class.

Estimate the mean monthly expenditures.