Exam 9: Estimation From Sample Data

Closed caption movies allow the hearing impaired to enjoy the dialogue as well as the acting.A local organization for the hearing impaired people of the community takes a random sample of 100 movie listings offered by the cable television company in order to estimate the proportion of closed caption movies offered.Fourteen movies were closed caption.The cable television company says at least 5% of the movies shown are closed captioned.Prepare a 90% confidence interval for the true proportion, $\pi$ . to Comment on the cable television company's claim.

(Essay)

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Question 121

In surveying a simple random sample of 1000 assistant professors,we found that 573 of them felt they were underpaid by at least $3500.Based on these results,we have a 95% confidence that the proportion of the population of assistant professors who share this sentiment is between .548 and .598. Identify the point estimate of the population proportion.

(Short Answer)

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Question 122

In the formula $\bar { x } \pm z _ { \alpha / 2 } ( ?/ \sqrt { n } )$ ,the subscript $( \alpha / 2 )$ refers to the:

(Multiple Choice)

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Question 123

A glass company produces panes of glass that have specifications for a thickness of 0.3 inches.The process standard deviation is known to be 0.04 inches.A random sample of 45 panes of glass has an average thickness of 0.322 inches.What is the 90% confidence interval around the mean? What can we say about this process?

(Essay)

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Question 124

When an interval estimate is associated with a degree of confidence that it actually includes the population parameter of interest,it is referred to as a ____________________.

(Short Answer)

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Question 125

In an effort to estimate the proportion of female shoppers at a particular store,175 customers were randomly selected,of which 110 were female.Which of the following would represent a 90% confidence interval around this sample proportion?

(Multiple Choice)

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Question 126

U.S.News and World Report each year conducts a survey of starting salaries in various career fields.If you were to devise a plan to replicate this study,how large a sample would you need to take to be 98% certain that your estimate is within $500 of the true mean starting salary? Assume that $\text { σ }$ is $3500.

(Short Answer)

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Question 127

For a sample of size 20 taken from a normally distributed population with standard deviation equal to 5,a 90% confidence interval for the population mean would require the use of:

(Multiple Choice)

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Question 128

A simple random sample of 10 students is selected from a large college.For the 10 students,the number of days each was absent during the last semester was to be 3,7,2,1,0,2,4,2,6,and 2.What is the point estimate for $\text { σ }$ ,the standard deviation of the number of days absent for the college's students?

(Short Answer)

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Question 129

Interval limits refer to the upper and lower values of the ____________________.

(Short Answer)

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Question 130

A proponent of private aid to assist those who are suffering from hunger has decided to take a random sample to estimate the average annual contribution in her community to world hunger relief.A similar study in a comparable community reported the standard deviation of giving as $15.Our proponent believes that her estimate, $\bar { x }$ ,should be within $3 of the true average and with 92-percent confidence.If the community population is 1000,determine the appropriate sample size.

(Short Answer)

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Question 131

A proponent of private aid to assist those who are suffering from hunger has decided to take a random sample to estimate the average annual contribution in her community to world hunger relief.A similar study in a comparable community reported the standard deviation of giving as $15.Our proponent believes that her estimate, $\bar { x }$ ,should be within $3 of the true average and with 92-percent confidence.What size sample is appropriate?

(Short Answer)

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Question 132

If the population mean $\mu$ is unknown,one can use sample data as the basis from which to make probability statements about the true (but unknown)value of $\mu$ .

(True/False)

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Question 133

A cost accountant wishes to establish the average amount, $\mu$ ,spent by executives per day on travel and lodging.The population standard deviation $\text { σ }$ = $29.The accountant wants to be 90-percent confident that the estimate, $\bar { x }$ ,obtained is within $7 of the true mean.How large a sample is needed if the company employs 263 executives?

(Short Answer)

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Question 134

In developing an interval estimate for a population mean,a sample of 50 observations was used.The interval estimate was 19.76 $\pm$ 1.32.Had the sample size been 200 instead of 50,the interval estimate would have been:

(Multiple Choice)

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Question 135

Cement for building a dam is delivered by truck.The dispatcher wants to estimate the average driver time required to load,drive to the dam,unload,and drive back to the plant.The time is assumed to be normally distributed.Total time required is recorded for a random sample of 18 with a mean of 543.71 and a standard deviation of 69.83.Use these data to obtain an 80-percent confidence interval for the average driver time. to

(Short Answer)

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Question 136

Determine the limits of the 88% confidence interval for $\mu$ ,given that n = 72; $\bar { x }$ = 18; and $\text { σ }$ = 6. to .

(Short Answer)

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Question 137

The economics department secretary wants to estimate the average number of bottled drinks sold each day out of the vending machine.Similar vending machine sales have a standard deviation of 9 bottles per day.He wants to be 95-percent confident that the estimate, $\bar { x }$ ,obtained is within 3 bottles of the true mean $\mu$ .How large a sample is needed if the limit of the Coke machine for one day is 120?

(Short Answer)

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Question 138

A marketing class is engaged in a project to estimate the proportion of homes receiving both HBO and ShowTime cable service.The class plans to use a confidence coefficient of 0.95 and a maximum error of the estimate equal to 0.10.Determine the sample size for the class to use assuming a city population of 2500.

(Short Answer)

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Question 139

Determine the limits of the 75% confidence interval for $\mu$ ,given that n = 90; $\bar { x }$ = 50; and $\text { σ}$ = 12. to

(Short Answer)

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Question 140

Showing 121 - 140 of 150

In the formula $\bar { x } \pm z _ { \alpha / 2 } ( ?/ \sqrt { n } )$ ,the subscript $( \alpha / 2 )$ refers to the:

When an interval estimate is associated with a degree of confidence that it actually includes the population parameter of interest,it is referred to as a ____________________.

In an effort to estimate the proportion of female shoppers at a particular store,175 customers were randomly selected,of which 110 were female.Which of the following would represent a 90% confidence interval around this sample proportion?

For a sample of size 20 taken from a normally distributed population with standard deviation equal to 5,a 90% confidence interval for the population mean would require the use of:

Interval limits refer to the upper and lower values of the ____________________.

If the population mean $\mu$ is unknown,one can use sample data as the basis from which to make probability statements about the true (but unknown)value of $\mu$ .

In developing an interval estimate for a population mean,a sample of 50 observations was used.The interval estimate was 19.76 $\pm$ 1.32.Had the sample size been 200 instead of 50,the interval estimate would have been:

Determine the limits of the 88% confidence interval for $\mu$ ,given that n = 72; $\bar { x }$ = 18; and $\text { σ }$ = 6. to .

Determine the limits of the 75% confidence interval for $\mu$ ,given that n = 90; $\bar { x }$ = 50; and $\text { σ}$ = 12. to

A Preview of Business Statistics

Visual Description of Data

Statistical Description of Data

Data Collection and Sampling Methods

Probability: Review of Basic Concepts

Discrete Probability Distributions

Continuous Probability Distributions

Sampling Distributions

Hypothesis Tests Involving a Sample Mean or Proportion

Hypothesis Tests Involving Two Sample Means

Analysis of Variance Tests

Chi-Square Applications

Nonparametric Methods

Simple Linear Regression and Correlation

Multiple Regression and Correlation

Model Building

Models for Time Series and Forecasting

Decision Theory

Total Quality Management

Filters

Exam 9: Estimation From Sample Data

In the formula xˉ±zα/2(?/n)\bar { x } \pm z _ { \alpha / 2 } ( ?/ \sqrt { n } )xˉ±zα/2​(?/n​) ,the subscript (α/2)( \alpha / 2 )(α/2) refers to the:

When an interval estimate is associated with a degree of confidence that it actually includes the population parameter of interest,it is referred to as a ____________________.

In an effort to estimate the proportion of female shoppers at a particular store,175 customers were randomly selected,of which 110 were female.Which of the following would represent a 90% confidence interval around this sample proportion?

For a sample of size 20 taken from a normally distributed population with standard deviation equal to 5,a 90% confidence interval for the population mean would require the use of:

Interval limits refer to the upper and lower values of the ____________________.

If the population mean μ\muμ is unknown,one can use sample data as the basis from which to make probability statements about the true (but unknown)value of μ\muμ .

In developing an interval estimate for a population mean,a sample of 50 observations was used.The interval estimate was 19.76 ±\pm± 1.32.Had the sample size been 200 instead of 50,the interval estimate would have been:

Determine the limits of the 88% confidence interval for μ\muμ ,given that n = 72; xˉ\bar { x }xˉ = 18; and σ \text { σ } σ = 6. ____________________ to ____________________.

Determine the limits of the 75% confidence interval for μ\muμ ,given that n = 90; xˉ\bar { x }xˉ = 50; and σ\text { σ} σ = 12. ____________________ to ____________________

A Preview of Business Statistics

Visual Description of Data

Statistical Description of Data

Data Collection and Sampling Methods

Probability: Review of Basic Concepts

Discrete Probability Distributions

Continuous Probability Distributions

Sampling Distributions

Hypothesis Tests Involving a Sample Mean or Proportion

Hypothesis Tests Involving Two Sample Means

Analysis of Variance Tests

Chi-Square Applications

Nonparametric Methods

Simple Linear Regression and Correlation

Multiple Regression and Correlation

Model Building

Models for Time Series and Forecasting

Decision Theory

Total Quality Management

Filters

In the formula $\bar { x } \pm z _ { \alpha / 2 } ( ?/ \sqrt { n } )$ ,the subscript $( \alpha / 2 )$ refers to the:

If the population mean $\mu$ is unknown,one can use sample data as the basis from which to make probability statements about the true (but unknown)value of $\mu$ .

In developing an interval estimate for a population mean,a sample of 50 observations was used.The interval estimate was 19.76 $\pm$ 1.32.Had the sample size been 200 instead of 50,the interval estimate would have been:

Determine the limits of the 88% confidence interval for $\mu$ ,given that n = 72; $\bar { x }$ = 18; and $\text { σ }$ = 6. to .

Determine the limits of the 75% confidence interval for $\mu$ ,given that n = 90; $\bar { x }$ = 50; and $\text { σ}$ = 12. to