Question 1

The width of the confidence interval estimate of the population mean μ is a function of only two quantities: the population standard deviation σ and the sample size n.

Accepted Answer

A) True 
 B)False

Question 2

The temperature readings for 20 fall days (degrees Fahrenheit)in Wheeling,West Virginia,are normally distributed with a mean of 5.5 degrees and a standard deviation of 1.5 degrees.Determine the 90% confidence interval estimate for the fall mean temperature.

Accepted Answer

The answer of The temperature readings for 20 fall days...

Question 3

Determine the sample size that is required to estimate a population mean to within 0.4 units with a 99% confidence when the population standard deviation is 1.75.

Accepted Answer

The answer of Determine the sample size that is required...

Question 4

The librarian at the New York City Public Library has asked her assistant for an interval estimate of the mean number of books checked out each day.The assistant took a sample and found the mean to be 880 books.She provides the librarian with an interval estimate of between 790 and 970 books checked out per day.An efficient,unbiased point estimate of the number of books checked out each day at the New York City Public Library is:

Accepted Answer

A) 790 
B) 880 
C) 90 
D) None of these choices.

Question 5

Time Spent Playing Computer Games 
Suppose that the amount of time teenagers spend playing computer games per week is normally distributed with a standard deviation of 1.5 hours.A sample of 100 teenagers is selected at random,and the sample mean computed as 6.5 hours. ​ ​
-{Time Spent Playing Computer Games Narrative} Determine the 95% confidence interval estimate of the population mean if the sample size is changed to 36.

Accepted Answer

The answer of Time Spent Playing Computer Games 
Suppose that...

Question 6

When constructing confidence interval for a parameter,we generally set the confidence level 1 − α close to 1 (usually between 0.90 and 0.99)because it is the probability that the interval includes the actual value of the population parameter.

Accepted Answer

A) True 
 B)False

Question 7

Time Spent Playing Computer Games 
Suppose that the amount of time teenagers spend playing computer games per week is normally distributed with a standard deviation of 1.5 hours.A sample of 100 teenagers is selected at random,and the sample mean computed as 6.5 hours. ​ ​
-{Time Spent Playing Computer Games Narrative} Determine the 95% confidence interval estimate of the population mean if the sample size is changed to 300.

Accepted Answer

The answer of Time Spent Playing Computer Games 
Suppose that...

Question 8

The confidence ____________________ is the chance that the interval contains the parameter,over repeated sampling.

Accepted Answer

The answer of The confidence ____________________ is the chance that...

Question 9

A survey of 100 businesses revealed that the mean after-tax profit was $80,000.Assume the population standard deviation is $15,000:
a.Determine the 95% confidence interval estimate of the mean after-tax profit for all businesses.
b.Explain why you can use the confidence interval formula here,even though the population is not necessarily normal.

Accepted Answer

The answer of A survey of 100 businesses revealed that...

Question 10

A random sample of 10 university students was surveyed to determine the amount of time spent weekly at the library.The times are: 13,14,5,6,8,10,7,12,15,and 3.If the times are normally distributed with a standard deviation of 5.2 hours,estimate with 90% confidence the mean weekly time at the library by all university students.

Accepted Answer

The answer of A random sample of 10 university students...

Question 11

Time Spent Playing Computer Games 
Suppose that the amount of time teenagers spend playing computer games per week is normally distributed with a standard deviation of 1.5 hours.A sample of 100 teenagers is selected at random,and the sample mean computed as 6.5 hours. ​ ​
-{Time Spent Playing Computer Games Narrative} Determine the 95% confidence interval estimate of the population mean if the population standard deviation is changed to 1.2.

Accepted Answer

The answer of Time Spent Playing Computer Games 
Suppose that...

Question 12

The sample variance s2 is an unbiased estimator of the population variance σ2 when the denominator of s2 is n.

Accepted Answer

A) True 
 B)False

Question 13

An engineer for an electric fencing company is interested in the mean length of wires being cut automatically by machine.The desired length of the wires is 12 feet.It is known that the standard deviation in the cutting length is 0.15 feet.Suppose the engineer decided to estimate the mean length to within 0.025 with 99% confidence.What sample size would be needed?

Accepted Answer

The answer of An engineer for an electric fencing company...

Question 14

The error of estimation is the ____________________ between an estimator and the parameter.

Accepted Answer

The answer of The error of estimation is the ____________________...

Question 15

In determining the sample size n needed to estimate the population mean,n decreases as the desired width of the confidence interval decreases.

Accepted Answer

A) True 
 B)False

Question 16

It is ____________________ to say that a 95% confidence interval means there is a 95% chance that the parameter lies in that confidence interval.

Accepted Answer

The answer of It is ____________________ to say that a...

Question 17

In determining the sample size n needed to estimate the population mean,n is higher if the population standard deviation σ is higher.

Accepted Answer

A) True 
 B)False

Question 18

College Dean
 A college dean would like to estimate a population mean to within 40 units with 99% confidence given that the population standard deviation is 200. ​ ​
-{College Dean Narrative} What sample size should be used?

Accepted Answer

The answer of College Dean
 A college dean would like...

Question 19

The sample size needed to estimate a population mean to within 1 unit with 90% confidence given that the population standard deviation is 10 is 17.

Accepted Answer

A) True 
 B)False

Question 20

We do not have control over the population standard deviation when forming a confidence interval,but we can control the ____________________ and the ____________________.

Accepted Answer

The answer of We do not have control over the...

Exam 10: Introduction to Estimation

The width of the confidence interval estimate of the population mean μ is a function of only two quantities: the population standard deviation σ and the sample size n.

The temperature readings for 20 fall days (degrees Fahrenheit)in Wheeling,West Virginia,are normally distributed with a mean of 5.5 degrees and a standard deviation of 1.5 degrees.Determine the 90% confidence interval estimate for the fall mean temperature.

Determine the sample size that is required to estimate a population mean to within 0.4 units with a 99% confidence when the population standard deviation is 1.75.

When constructing confidence interval for a parameter,we generally set the confidence level 1 − α close to 1 (usually between 0.90 and 0.99)because it is the probability that the interval includes the actual value of the population parameter.

The confidence ____________________ is the chance that the interval contains the parameter,over repeated sampling.

The sample variance s² is an unbiased estimator of the population variance σ² when the denominator of s² is n.

The error of estimation is the ____________________ between an estimator and the parameter.

In determining the sample size n needed to estimate the population mean,n decreases as the desired width of the confidence interval decreases.

It is ____________________ to say that a 95% confidence interval means there is a 95% chance that the parameter lies in that confidence interval.

In determining the sample size n needed to estimate the population mean,n is higher if the population standard deviation σ is higher.

College Dean A college dean would like to estimate a population mean to within 40 units with 99% confidence given that the population standard deviation is 200. -{College Dean Narrative} What sample size should be used?

The sample size needed to estimate a population mean to within 1 unit with 90% confidence given that the population standard deviation is 10 is 17.

We do not have control over the population standard deviation when forming a confidence interval,but we can control the and the .

Exam 10: Introduction to Estimation

The width of the confidence interval estimate of the population mean μ is a function of only two quantities: the population standard deviation σ and the sample size n.

The temperature readings for 20 fall days (degrees Fahrenheit)in Wheeling,West Virginia,are normally distributed with a mean of 5.5 degrees and a standard deviation of 1.5 degrees.Determine the 90% confidence interval estimate for the fall mean temperature.

Determine the sample size that is required to estimate a population mean to within 0.4 units with a 99% confidence when the population standard deviation is 1.75.

When constructing confidence interval for a parameter,we generally set the confidence level 1 − α close to 1 (usually between 0.90 and 0.99)because it is the probability that the interval includes the actual value of the population parameter.

The confidence ____________________ is the chance that the interval contains the parameter,over repeated sampling.

The sample variance s2 is an unbiased estimator of the population variance σ2 when the denominator of s2 is n.

The error of estimation is the ____________________ between an estimator and the parameter.

In determining the sample size n needed to estimate the population mean,n decreases as the desired width of the confidence interval decreases.

It is ____________________ to say that a 95% confidence interval means there is a 95% chance that the parameter lies in that confidence interval.

In determining the sample size n needed to estimate the population mean,n is higher if the population standard deviation σ is higher.

College Dean A college dean would like to estimate a population mean to within 40 units with 99% confidence given that the population standard deviation is 200. ​ ​ -{College Dean Narrative} What sample size should be used?

The sample size needed to estimate a population mean to within 1 unit with 90% confidence given that the population standard deviation is 10 is 17.

We do not have control over the population standard deviation when forming a confidence interval,but we can control the ____________________ and the ____________________.

The sample variance s² is an unbiased estimator of the population variance σ² when the denominator of s² is n.

College Dean A college dean would like to estimate a population mean to within 40 units with 99% confidence given that the population standard deviation is 200. -{College Dean Narrative} What sample size should be used?

We do not have control over the population standard deviation when forming a confidence interval,but we can control the and the .