Question 1

To compute the necessary sample size for an interval estimate of a population proportion, all of the following procedures are recommended when p is unknown except​

Accepted Answer

A)  ​use the sample proportion from a previous study. 
B)  ​use the sample proportion from a preliminary sample. 
C)  ​use 1.0 as an estimate. 
D)  ​use judgment or a best guess. 
A)  ​use the sample proportion from a previous study. 
B)  ​use the sample proportion from a preliminary sample. 
C)  ​use 1.0 as an estimate. 
D)  ​use judgment or a best guess. C

Question 2

A 95% confidence interval for a population mean is determined to be 100 to 120.For the same data, if the confidence coefficient is reduced to .90, the confidence interval for μ

Accepted Answer

A)  becomes narrower. 
B)  becomes wider. 
C)  does not change. 
D)  becomes 100.1 to 120.1. 
A)  becomes narrower. 
B)  becomes wider. 
C)  does not change. 
D)  becomes 100.1 to 120.1. A

Question 3

Many people who bought X-Game gaming systems over the holidays have complained that the systems they purchased were defective.In a sample of 1200 units sold, 18 units were defective.
a.
Determine a 95% confidence interval for the percentage of defective systems in the population.
b.
If 1.5 million X-Game gaming systems were sold over the holidays, determine an interval for the number of defectives in sales.

Accepted Answer

​
a.
.00812 to .02188 (rounded)
b.
12,184 to 32,816 (using unrounded estimates)

Question 4

Information regarding the price of a roll of camera film (35 mm, 24 exposure) for a sample of 12 cities worldwide is shown below.Determine a 95% confidence interval for the population mean assuming that the population is normally distributed.

Accepted Answer

3.736 to 6

Question 5

A sample of 100 information systems managers had an average hourly income of $40.00 with a standard deviation of $8.00.The value of the margin of error at 95% confidence is

Accepted Answer

A)  80. 
B)  8. 
C)  .10. 
D)  1.568. 
A)  80. 
B)  8. 
C)  .10. 
D)  1.568.

Question 6

The manager of a grocery store has taken a random sample of 144 customers.The average length of time it took these 144 customers to check out was 3 minutes.It is known that the standard deviation of the population of checkout times is 1 minute.The standard error of the mean equals

Accepted Answer

A)  .008. 
B)  .833. 
C)  .083. 
D)  1.000. 
A)  .008. 
B)  .833. 
C)  .083. 
D)  1.000.

Question 7

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

Accepted Answer

A)  normal distribution. 
B)  t distribution. 
C)  mean of the sample. 
D)  mean of the population. 
A)  normal distribution. 
B)  t distribution. 
C)  mean of the sample. 
D)  mean of the population.

Question 8

The proprietor of a boutique in New York wanted to determine the average age of his customers.A random sample of 53 customers revealed an average age of 28 years with a standard deviation of 4 years.Determine a 98% confidence interval estimate for the average age of all his customers.

Accepted Answer

26.68 to 2

Question 9

A statistician selected a sample of 16 accounts receivable and determined the mean of the sample to be $5000 with a standard deviation of $400.He reported that the sample information indicated the mean of the population ranges from $4739.80 to $5260.20.He neglected to report what confidence coefficient he had used.Based on the above information, determine the confidence coefficient that was used.Assume the population has a normal distribution.

Accepted Answer

The answer of A statistician selected a sample of 16...

Question 10

The manager of a department store wants to determine the proportion of people who use the store's credit cards for their purchases.What sample size should he take so that, at 95% confidence, the error will not be more than 6%?

Accepted Answer

The answer of The manager of a department store wants...

Question 11

In November 2018, 50,000 people living in the United States were asked whether they had a computer at home.43,128 answered yes, they had a computer at home.Provide a 99% confidence interval for the proportion of people living in the United States who have a computer at home.

Accepted Answer

A)  .862546 to .862573 
B)  .8586 to .8665 
C)  .8595 to .8656 
D)  .862548 to .862578 
A)  .862546 to .862573 
B)  .8586 to .8665 
C)  .8595 to .8656 
D)  .862548 to .862578

Question 12

You are given the following information obtained from a sample of 5 observations taken from a population that has a normal distribution.   ​
Develop a 98% confidence interval estimate for the mean of the population.

Accepted Answer

62.69 to 9

Question 13

A machine that produces a major part for an airplane engine is monitored closely.In the past, 6% of the parts produced would be defective.With a .95 probability, the sample size that needs to be taken if the desired margin of error is .04 or less is

Accepted Answer

A)  70. 
B)  69. 
C)  135. 
D)  136. 
A)  70. 
B)  69. 
C)  135. 
D)  136.

Question 14

As the number of degrees of freedom for a t distribution increases, the difference between the t distribution and the standard normal distribution

Accepted Answer

A)  becomes larger. 
B)  becomes smaller. 
C)  stays the same. 
D)  fluctuates. 
A)  becomes larger. 
B)  becomes smaller. 
C)  stays the same. 
D)  fluctuates.

Question 15

The t distribution is a family of similar probability distributions, with each individual distribution depending on a parameter known as the​

Accepted Answer

A)  ​finite correction factor. 
B)  ​sample size. 
C)  ​degrees of freedom. 
D)  ​standard deviation. 
A)  ​finite correction factor. 
B)  ​sample size. 
C)  ​degrees of freedom. 
D)  ​standard deviation.

Question 16

The Highway Safety Department wants to study the driving habits of individuals.A sample of 121 cars traveling on the highway revealed an average speed of 60 miles per hour with a standard deviation of 11 miles per hour.Determine a 95% confidence interval estimate for the speed of all cars.

Accepted Answer

58.04 to 6

Question 17

The manager of a grocery store has taken a random sample of 144 customers.The average length of time it took these 144 customers to check out was 3 minutes.It is known that the standard deviation of the population of checkout times is 1 minute.With a .95 probability, the sample mean will provide a margin of error of

Accepted Answer

A)  1.63. 
B)  .137. 
C)  .163. 
D)  1.37. 
A)  1.63. 
B)  .137. 
C)  .163. 
D)  1.37.

Question 18

Choo Choo Paper Company produces papers of various thickness.A random sample of 300 cuts of a specific variety had a mean thickness of 35.3 mils with a standard deviation of 5 mils.Develop a 95% confidence interval for the mean thickness of the population.

Accepted Answer

The answer of Choo Choo Paper Company produces papers of...

Question 19

Below you are given ages that were obtained by taking a random sample of 6 undergraduate instructors at a university.Assume the population has a normal distribution.   ​ 
a.
What is the point estimate of μ?
b.
Determine the standard deviation.
c.
Construct a 90% confidence interval for the average age of undergraduate instructors.
d.
Construct a 99% confidence interval for the average age of undergraduate instructors.
e.
Discuss why the 90% and 99% confidence intervals are different.

Accepted Answer

​
a.
40 years
b.
2.19 (rounded

Question 20

A researcher is interested in determining the average number of years of employee retention in a company.If past information shows a population standard deviation of 9 months, what sample size should be taken so that, at 95% confidence, the margin of error will be 3 months or less?

Accepted Answer

The answer of A researcher is interested in determining the...

To compute the necessary sample size for an interval estimate of a population proportion, all of the following procedures are recommended when p is unknown except

A 95% confidence interval for a population mean is determined to be 100 to 120.For the same data, if the confidence coefficient is reduced to .90, the confidence interval for μ

Information regarding the price of a roll of camera film (35 mm, 24 exposure) for a sample of 12 cities worldwide is shown below.Determine a 95% confidence interval for the population mean assuming that the population is normally distributed.

A sample of 100 information systems managers had an average hourly income of $40.00 with a standard deviation of $8.00.The value of the margin of error at 95% confidence is

The manager of a grocery store has taken a random sample of 144 customers.The average length of time it took these 144 customers to check out was 3 minutes.It is known that the standard deviation of the population of checkout times is 1 minute.The standard error of the mean equals

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

The proprietor of a boutique in New York wanted to determine the average age of his customers.A random sample of 53 customers revealed an average age of 28 years with a standard deviation of 4 years.Determine a 98% confidence interval estimate for the average age of all his customers.

The manager of a department store wants to determine the proportion of people who use the store's credit cards for their purchases.What sample size should he take so that, at 95% confidence, the error will not be more than 6%?

In November 2018, 50,000 people living in the United States were asked whether they had a computer at home.43,128 answered yes, they had a computer at home.Provide a 99% confidence interval for the proportion of people living in the United States who have a computer at home.

You are given the following information obtained from a sample of 5 observations taken from a population that has a normal distribution. Develop a 98% confidence interval estimate for the mean of the population.

A machine that produces a major part for an airplane engine is monitored closely.In the past, 6% of the parts produced would be defective.With a .95 probability, the sample size that needs to be taken if the desired margin of error is .04 or less is

As the number of degrees of freedom for a t distribution increases, the difference between the t distribution and the standard normal distribution

The t distribution is a family of similar probability distributions, with each individual distribution depending on a parameter known as the

The Highway Safety Department wants to study the driving habits of individuals.A sample of 121 cars traveling on the highway revealed an average speed of 60 miles per hour with a standard deviation of 11 miles per hour.Determine a 95% confidence interval estimate for the speed of all cars.

Choo Choo Paper Company produces papers of various thickness.A random sample of 300 cuts of a specific variety had a mean thickness of 35.3 mils with a standard deviation of 5 mils.Develop a 95% confidence interval for the mean thickness of the population.

A researcher is interested in determining the average number of years of employee retention in a company.If past information shows a population standard deviation of 9 months, what sample size should be taken so that, at 95% confidence, the margin of error will be 3 months or less?

Data and Statistics

Descriptive Statistics: Tabular and Graphical Displays

Descriptive Statistics: Numerical Measures

Introduction to Probability

Discrete Probability Distributions

Continuous Probability Distributions

Sampling and Sampling Distributions

Hypothesis Tests

Inference About Means and Proportions With Two Populations

Inferences About Population Variances

Comparing Multiple Proportions, Tests of Independence and Goodness of Fit

Experimental Design and Analysis of Variance

Simple Linear Regression

Multiple Regression

Filters

Exam 8: Interval Estimation

To compute the necessary sample size for an interval estimate of a population proportion, all of the following procedures are recommended when p is unknown except​

A 95% confidence interval for a population mean is determined to be 100 to 120.For the same data, if the confidence coefficient is reduced to .90, the confidence interval for μ

Information regarding the price of a roll of camera film (35 mm, 24 exposure) for a sample of 12 cities worldwide is shown below.Determine a 95% confidence interval for the population mean assuming that the population is normally distributed.

A sample of 100 information systems managers had an average hourly income of $40.00 with a standard deviation of $8.00.The value of the margin of error at 95% confidence is

The manager of a grocery store has taken a random sample of 144 customers.The average length of time it took these 144 customers to check out was 3 minutes.It is known that the standard deviation of the population of checkout times is 1 minute.The standard error of the mean equals

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

The proprietor of a boutique in New York wanted to determine the average age of his customers.A random sample of 53 customers revealed an average age of 28 years with a standard deviation of 4 years.Determine a 98% confidence interval estimate for the average age of all his customers.

The manager of a department store wants to determine the proportion of people who use the store's credit cards for their purchases.What sample size should he take so that, at 95% confidence, the error will not be more than 6%?

In November 2018, 50,000 people living in the United States were asked whether they had a computer at home.43,128 answered yes, they had a computer at home.Provide a 99% confidence interval for the proportion of people living in the United States who have a computer at home.

You are given the following information obtained from a sample of 5 observations taken from a population that has a normal distribution. ​ Develop a 98% confidence interval estimate for the mean of the population.

A machine that produces a major part for an airplane engine is monitored closely.In the past, 6% of the parts produced would be defective.With a .95 probability, the sample size that needs to be taken if the desired margin of error is .04 or less is

As the number of degrees of freedom for a t distribution increases, the difference between the t distribution and the standard normal distribution

The t distribution is a family of similar probability distributions, with each individual distribution depending on a parameter known as the​

The Highway Safety Department wants to study the driving habits of individuals.A sample of 121 cars traveling on the highway revealed an average speed of 60 miles per hour with a standard deviation of 11 miles per hour.Determine a 95% confidence interval estimate for the speed of all cars.

Choo Choo Paper Company produces papers of various thickness.A random sample of 300 cuts of a specific variety had a mean thickness of 35.3 mils with a standard deviation of 5 mils.Develop a 95% confidence interval for the mean thickness of the population.

A researcher is interested in determining the average number of years of employee retention in a company.If past information shows a population standard deviation of 9 months, what sample size should be taken so that, at 95% confidence, the margin of error will be 3 months or less?

Data and Statistics

Descriptive Statistics: Tabular and Graphical Displays

Descriptive Statistics: Numerical Measures

Introduction to Probability

Discrete Probability Distributions

Continuous Probability Distributions

Sampling and Sampling Distributions

Hypothesis Tests

Inference About Means and Proportions With Two Populations

Inferences About Population Variances

Comparing Multiple Proportions, Tests of Independence and Goodness of Fit

Experimental Design and Analysis of Variance

Simple Linear Regression

Multiple Regression

Filters

To compute the necessary sample size for an interval estimate of a population proportion, all of the following procedures are recommended when p is unknown except

You are given the following information obtained from a sample of 5 observations taken from a population that has a normal distribution. Develop a 98% confidence interval estimate for the mean of the population.

The t distribution is a family of similar probability distributions, with each individual distribution depending on a parameter known as the