Exam 9: Estimation From Sample Data

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.She 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?

(Short Answer)

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Question 61

A production manager is concerned with the average weight of metal ingots.From past data,she knows that $\text { ? }$ is 1.6 lbs.The manager wishes to make a 95% interval estimate for $\mu$ using a sample of 64 ingots.The accuracy of this sample in estimating the population mean will be:

(Multiple Choice)

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Question 62

The lower limit of a confidence interval at the 95% level of confidence for the population proportion if a sample of size 200 had 40 successes is:

(Multiple Choice)

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Question 63

The Ford Motor Company is interested in consumer acceptance of its subcompact car based on the proportion of positive responses to a survey.How large a survey must the company take to have 95% confidence and no more than 0.01 error?

(Multiple Choice)

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Question 64

If the population cannot be assumed to be normal distributed,the sample size must be at least ____________________ for the central limit theorem to apply.

(Short Answer)

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Question 65

A rechargeable flashlight is advertised to last up to 2 1/2 hours per charge and to recharge overnight.A test was conducted which measured the time a light lasted before needing a recharge.A random sample of 12 lights has a mean recharge time of 2.24 hours and a standard deviation of 1.05 hours.Assuming the population for recharge time is normally distributed,what is the 99% confidence interval estimate for the population mean? to

(Short Answer)

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Question 66

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 confidence interval estimate for the population proportion. to .

(Short Answer)

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Question 67

A city-paid consumer advocate wants to secure information about the mean length, $\mu$ ,of coin-separated car wash cycles.A previous study reported the standard deviation of the length of car wash cycles to be 6 minutes.The advocate timed the wash cycle at 81 randomly selected car wash locations and the mean of the sample was 4.8 minutes.The 90 percent confidence interval estimate is 3.70 to 5.90 minutes.Interpret this interval.

(Short Answer)

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Question 68

In an effort to determine the average loaded weight of trucks leaving a gypsum wallboard plant,a random sample is to be taken.The population standard deviation is 2500 lbs.A 90-percent confidence interval is to be used and the average, $\mu$ ,is to be estimated within 500 pounds.Determine the sample size needed.

(Short Answer)

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Question 69

A mother who is interested in the true proportion of R-rated movies shown on pay TV by a cable system randomly selects 98 listings and finds 14 of them are R-rated movies.In her report to the subcommittee she wants to be 98% confident that the true proportion will be in an interval which she states.She has asked you to assist her by preparing a 98% confidence interval based on the data she collected.What should she report? to

(Short Answer)

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Question 70

What is an interval estimate?

(Essay)

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Question 71

In determining the necessary sample size in making an interval estimate for a population mean,it is necessary to first make an estimate of the population standard deviation.

(True/False)

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Question 72

A manufacturer of salad dressings uses machines to dispense liquid ingredients into bottles that move along a filling line.The machine that dispenses dressings is working properly when 8 ounces are dispensed.The standard deviation of the process is 0.15 ounces.Suppose that the average amount dispensed in a particular sample of 50 bottles is 7.952 ounces.Develop a 99% confidence interval around this sample mean.

(Short Answer)

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Question 73

Accuracy,or sampling error,is equal to one-half of the confidence interval width.

(True/False)

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Question 74

Whenever sample data are used for estimating a population mean or proportion,sampling error will not be present,since the observed sample statistic ( $\bar { x }$ or p)will not differ from the actual value of the population parameter ( $\mu$ or $\pi$ ).

(True/False)

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Question 75

A federal auditor for nationally chartered banks from a random sample of 100 accounts found that the average demand deposit balance at the First National Bank of small town was $549.82.If the auditor needed a point estimate for the population mean for all accounts at this bank,what would she use?

(Multiple Choice)

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Question 76

The technique used to determine a confidence interval to estimate a population proportion uses the normal distribution as an approximation to the Poisson distribution.

(True/False)

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Question 77

A random sample of thirty daily water productions (expressed in thousands)for a given city yielded a mean of 2489.067 and standard deviation of 74.67.What are the point estimates for the true mean daily water production and the point estimate for the variance of this population? Mean = Variance =

(Short Answer)

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Question 78

The use of sample information to draw conclusions about the population is known as ____________________.

(Short Answer)

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Question 79

A personnel manager is conducting a study of sales supervisory salaries in this industry.A survey for the salaries of 36 sales supervisors found a mean of $48.41 thousand and a standard deviation of $18.3 thousand.Determine a 98-percent confidence interval (in thousands of dollars)for the mean of all sales supervisory salaries in this industry. to

(Short Answer)

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Question 80

Showing 61 - 80 of 150

A production manager is concerned with the average weight of metal ingots.From past data,she knows that $\text { ? }$ is 1.6 lbs.The manager wishes to make a 95% interval estimate for $\mu$ using a sample of 64 ingots.The accuracy of this sample in estimating the population mean will be:

The lower limit of a confidence interval at the 95% level of confidence for the population proportion if a sample of size 200 had 40 successes is:

The Ford Motor Company is interested in consumer acceptance of its subcompact car based on the proportion of positive responses to a survey.How large a survey must the company take to have 95% confidence and no more than 0.01 error?

If the population cannot be assumed to be normal distributed,the sample size must be at least ____________________ for the central limit theorem to apply.

What is an interval estimate?

In determining the necessary sample size in making an interval estimate for a population mean,it is necessary to first make an estimate of the population standard deviation.

Accuracy,or sampling error,is equal to one-half of the confidence interval width.

Whenever sample data are used for estimating a population mean or proportion,sampling error will not be present,since the observed sample statistic ( $\bar { x }$ or p)will not differ from the actual value of the population parameter ( $\mu$ or $\pi$ ).

A federal auditor for nationally chartered banks from a random sample of 100 accounts found that the average demand deposit balance at the First National Bank of small town was $549.82.If the auditor needed a point estimate for the population mean for all accounts at this bank,what would she use?

The technique used to determine a confidence interval to estimate a population proportion uses the normal distribution as an approximation to the Poisson distribution.

A random sample of thirty daily water productions (expressed in thousands)for a given city yielded a mean of 2489.067 and standard deviation of 74.67.What are the point estimates for the true mean daily water production and the point estimate for the variance of this population? Mean = Variance =

The use of sample information to draw conclusions about the population is known as ____________________.

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

A production manager is concerned with the average weight of metal ingots.From past data,she knows that ? \text { ? } ? is 1.6 lbs.The manager wishes to make a 95% interval estimate for μ\muμ using a sample of 64 ingots.The accuracy of this sample in estimating the population mean will be:

The lower limit of a confidence interval at the 95% level of confidence for the population proportion if a sample of size 200 had 40 successes is:

The Ford Motor Company is interested in consumer acceptance of its subcompact car based on the proportion of positive responses to a survey.How large a survey must the company take to have 95% confidence and no more than 0.01 error?

If the population cannot be assumed to be normal distributed,the sample size must be at least ____________________ for the central limit theorem to apply.

What is an interval estimate?

In determining the necessary sample size in making an interval estimate for a population mean,it is necessary to first make an estimate of the population standard deviation.

Accuracy,or sampling error,is equal to one-half of the confidence interval width.

Whenever sample data are used for estimating a population mean or proportion,sampling error will not be present,since the observed sample statistic ( xˉ\bar { x }xˉ or p)will not differ from the actual value of the population parameter ( μ\muμ or π\piπ ).

A federal auditor for nationally chartered banks from a random sample of 100 accounts found that the average demand deposit balance at the First National Bank of small town was $549.82.If the auditor needed a point estimate for the population mean for all accounts at this bank,what would she use?

The technique used to determine a confidence interval to estimate a population proportion uses the normal distribution as an approximation to the Poisson distribution.

The use of sample information to draw conclusions about the population is known as ____________________.

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

A production manager is concerned with the average weight of metal ingots.From past data,she knows that $\text { ? }$ is 1.6 lbs.The manager wishes to make a 95% interval estimate for $\mu$ using a sample of 64 ingots.The accuracy of this sample in estimating the population mean will be:

Whenever sample data are used for estimating a population mean or proportion,sampling error will not be present,since the observed sample statistic ( $\bar { x }$ or p)will not differ from the actual value of the population parameter ( $\mu$ or $\pi$ ).