Exam 8: Interval Estimation

In order to determine an interval for the mean of a population with unknown standard deviation a sample of 61 items is selected.The mean of the sample is determined to be 23.The number of degrees of freedom for reading the t value is

(Multiple Choice)

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Question 21

When s is used to estimate $\sigma$ ,the margin of error is computed by using

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Question 22

In a random sample of 400 registered voters,120 indicated they plan to vote for Candidate A.Determine a 95% confidence interval for the proportion of all the registered voters who will vote for Candidate A.

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Question 23

Exhibit 8-2 A random sample of 121 automobiles traveling on an interstate showed an average speed of 65 mph.From past information,it is known that the standard deviation of the population is 22 mph. -Refer to Exhibit 8-2.If the confidence coefficient is reduced to 0.9,the standard error of the mean

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Question 24

The monthly incomes from a random sample of workers in a factory are shown below. a.Compute the standard error of the mean (in dollars). b.Compute the margin of error (in dollars)at 95% confidence. c.Compute a 95% confidence interval for the mean of the population.Assume the population has a normal distribution.Give your answer in dollars.

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Question 25

If the standard deviation of the lifetime of a vacuum cleaner is estimated to be 300 hours,how large of a sample must be taken in order to be 97% confident that the margin of error will not exceed 40 hours?

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Question 26

Exhibit 8-2 A random sample of 121 automobiles traveling on an interstate showed an average speed of 65 mph.From past information,it is known that the standard deviation of the population is 22 mph. -Refer to Exhibit 8-2.If we are interested in determining an interval estimate for $\mu$ at 96.6% confidence,the Z value to use is

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Question 27

A sample of 60 students from a large university is taken.The average age in the sample was 22 years with a standard deviation of 6 years.Construct a 95% confidence interval for the average age of the population.

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Question 28

Using an $\alpha$ = 0.04 a confidence interval for a population proportion is determined to be 0.65 to 0.75.If the level of significance is decreased,the interval for the population proportion

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Question 29

A local electronics firm wants to determine their average daily sales (in dollars. )A sample of the sales for 36 days revealed average sales of $139,000.Assume that the standard deviation of the population is known to be $12,000. a.Provide a 95% confidence interval estimate for the average daily sales. b.Provide a 97% confidence interval estimate for the average daily sales.

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Question 30

The t value for a 95% confidence interval estimation with 24 degrees of freedom is

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Question 31

Exhibit 8-3 The manager of a grocery store has taken a random sample of 100 customers.The average length of time it took these 100 customers to check out was 3.0 minutes.It is known that the standard deviation of the population of checkout times is one minute. -Refer to Exhibit 8-3.With a .95 probability,the sample mean will provide a margin of error of

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Question 32

Exhibit 8-2 A random sample of 121 automobiles traveling on an interstate showed an average speed of 65 mph.From past information,it is known that the standard deviation of the population is 22 mph. -Refer to Exhibit 8-2.If the sample size was 100 (other factors remain unchanged),the interval for $\mu$ would

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Question 33

You are given the following information obtained from a random sample of 5 observations taken from a large population. Construct a 95% confidence interval for the mean of the population,assuming the population has a normal distribution.

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Question 34

The absolute value of the difference between the point estimate and the population parameter it estimates is

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Question 35

A random sample of 53 observations was taken.The average in the sample was 90 with a variance of 400. a.Construct a 98% confidence interval for $\mu$ . b.Construct a 99% confidence interval for $\mu$ . c.Discuss why the 98% and 99% confidence intervals are different. d.What would you expect to happen to the confidence interval in Part a if the sample size was increased? Be sure to explain your answer.

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Question 36

The manager of a grocery store wants to determine what proportion of people who enter his store are his regular customers.What size sample should he take so that at 97% confidence the margin of error will not be more than 0.1?

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Question 37

An estimate of a population parameter that provides an interval of values believed to contain the value of the parameter is known as the

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Question 38

Whenever the population standard deviation is unknown and the population has a normal or near-normal distribution,which distribution is used in developing an interval estimation?

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Question 39

A sample of 20 items from a population with an unknown $\sigma$ is selected in order to develop an interval estimate of $\mu$ .Which of the following is not necessary?

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Question 40

Showing 21 - 40 of 131

In order to determine an interval for the mean of a population with unknown standard deviation a sample of 61 items is selected.The mean of the sample is determined to be 23.The number of degrees of freedom for reading the t value is

When s is used to estimate $\sigma$ ,the margin of error is computed by using

In a random sample of 400 registered voters,120 indicated they plan to vote for Candidate A.Determine a 95% confidence interval for the proportion of all the registered voters who will vote for Candidate A.

Exhibit 8-2 A random sample of 121 automobiles traveling on an interstate showed an average speed of 65 mph.From past information,it is known that the standard deviation of the population is 22 mph. -Refer to Exhibit 8-2.If the confidence coefficient is reduced to 0.9,the standard error of the mean

If the standard deviation of the lifetime of a vacuum cleaner is estimated to be 300 hours,how large of a sample must be taken in order to be 97% confident that the margin of error will not exceed 40 hours?

A sample of 60 students from a large university is taken.The average age in the sample was 22 years with a standard deviation of 6 years.Construct a 95% confidence interval for the average age of the population.

Using an $\alpha$ = 0.04 a confidence interval for a population proportion is determined to be 0.65 to 0.75.If the level of significance is decreased,the interval for the population proportion

The t value for a 95% confidence interval estimation with 24 degrees of freedom is

You are given the following information obtained from a random sample of 5 observations taken from a large population. Construct a 95% confidence interval for the mean of the population,assuming the population has a normal distribution.

The absolute value of the difference between the point estimate and the population parameter it estimates is

The manager of a grocery store wants to determine what proportion of people who enter his store are his regular customers.What size sample should he take so that at 97% confidence the margin of error will not be more than 0.1?

An estimate of a population parameter that provides an interval of values believed to contain the value of the parameter is known as the

Whenever the population standard deviation is unknown and the population has a normal or near-normal distribution,which distribution is used in developing an interval estimation?

A sample of 20 items from a population with an unknown $\sigma$ is selected in order to develop an interval estimate of $\mu$ .Which of the following is not necessary?

Data and Statistics

Descriptive Statistics: Tabular and Graphical Presentations

Descriptive Statistics: Numerical Measures

Introduction to Probability

Discrete Probability Distributions

Continuous Probability Distributions

Sampling and Sampling Distributions

Hypothesis Tests

Statistical Inference About Means and Proportions With Two Populations

Inferences About Population Variances

Tests of Goodness of Fit and Independence

Analysis of Variance and Experimental Design

Simple Linear Regression

Multiple Regression

Regression Analysis: Model Building

Index Numbers

Forecasting

Nonparametric Methods

Statistical Methods for Quality Control

Decision Analysis

Sample Survey

Filters

Exam 8: Interval Estimation

In order to determine an interval for the mean of a population with unknown standard deviation a sample of 61 items is selected.The mean of the sample is determined to be 23.The number of degrees of freedom for reading the t value is

When s is used to estimate σ\sigmaσ ,the margin of error is computed by using

In a random sample of 400 registered voters,120 indicated they plan to vote for Candidate A.Determine a 95% confidence interval for the proportion of all the registered voters who will vote for Candidate A.

Exhibit 8-2 A random sample of 121 automobiles traveling on an interstate showed an average speed of 65 mph.From past information,it is known that the standard deviation of the population is 22 mph. -Refer to Exhibit 8-2.If the confidence coefficient is reduced to 0.9,the standard error of the mean

If the standard deviation of the lifetime of a vacuum cleaner is estimated to be 300 hours,how large of a sample must be taken in order to be 97% confident that the margin of error will not exceed 40 hours?

A sample of 60 students from a large university is taken.The average age in the sample was 22 years with a standard deviation of 6 years.Construct a 95% confidence interval for the average age of the population.

Using an α\alphaα = 0.04 a confidence interval for a population proportion is determined to be 0.65 to 0.75.If the level of significance is decreased,the interval for the population proportion

The t value for a 95% confidence interval estimation with 24 degrees of freedom is

You are given the following information obtained from a random sample of 5 observations taken from a large population. Construct a 95% confidence interval for the mean of the population,assuming the population has a normal distribution.

The absolute value of the difference between the point estimate and the population parameter it estimates is

The manager of a grocery store wants to determine what proportion of people who enter his store are his regular customers.What size sample should he take so that at 97% confidence the margin of error will not be more than 0.1?

An estimate of a population parameter that provides an interval of values believed to contain the value of the parameter is known as the

Whenever the population standard deviation is unknown and the population has a normal or near-normal distribution,which distribution is used in developing an interval estimation?

A sample of 20 items from a population with an unknown σ\sigmaσ is selected in order to develop an interval estimate of μ\muμ .Which of the following is not necessary?

Data and Statistics

Descriptive Statistics: Tabular and Graphical Presentations

Descriptive Statistics: Numerical Measures

Introduction to Probability

Discrete Probability Distributions

Continuous Probability Distributions

Sampling and Sampling Distributions

Hypothesis Tests

Statistical Inference About Means and Proportions With Two Populations

Inferences About Population Variances

Tests of Goodness of Fit and Independence

Analysis of Variance and Experimental Design

Simple Linear Regression

Multiple Regression

Regression Analysis: Model Building

Index Numbers

Forecasting

Nonparametric Methods

Statistical Methods for Quality Control

Decision Analysis

Sample Survey

Filters

When s is used to estimate $\sigma$ ,the margin of error is computed by using

Using an $\alpha$ = 0.04 a confidence interval for a population proportion is determined to be 0.65 to 0.75.If the level of significance is decreased,the interval for the population proportion

A sample of 20 items from a population with an unknown $\sigma$ is selected in order to develop an interval estimate of $\mu$ .Which of the following is not necessary?