Question 1

Tire Rotation
 The manager of a service station is in the process of analyzing the number of times car owners rotate the tires on their cars.She believes that the average motorist rotates his or her car's tires less frequently than recommended by the owner's manual (two times per year).In a preliminary survey she asked 14 car owners how many times they rotated their cars' tires in the last 12 months.The results are 1,1,2,0,3,3,0,1,0,1,2,3,3,and 1. ​ ​
-{Tire Rotation Narrative} Does this data provide sufficient evidence at the 10% significance level to indicate that the manager is correct?

Accepted Answer

The answer of Tire Rotation
 The manager of a service...

Question 2

____________________ populations allow us to use the confidence interval estimate of a mean to produce a confidence interval estimate of the population total.

Accepted Answer

The answer of ____________________ populations allow us to use the...

Question 3

Because of the greater uncertainty,the t-statistic will display greater ____________________ than the z-statistic.

Accepted Answer

The answer of Because of the greater uncertainty,the t-statistic will...

Question 4

Single Mothers' Ages
 A random sample of 10 single mothers was drawn from a Obstetrics Clinic.Their ages are 22,17,27,20,23,19,24,18,19,and 24 years. ​ ​
-{Single Mothers' Ages Narrative} Test to determine if we can infer at the 5% significance level that the population mean is not equal to 20.

Accepted Answer

The answer of Single Mothers' Ages
 A random sample of...

Question 5

When the population standard deviation is ____________________ and the population is normal,the test statistic for testing hypotheses about μ is the t-distribution with n − 1 degrees of freedom.

Accepted Answer

The answer of When the population standard deviation is ____________________...

Question 6

Hourly Fees 
A random sample of 15 hourly fees for car washers (including tips)was drawn from a normal population.The sample mean and sample standard deviation were  = $14.9 and s = $6.75. ​ ​
-{Hourly Fees Narrative} Can we infer at the 5% significance level that the mean fee for car washers (including tips)is greater than 12?

Accepted Answer

The answer of  Hourly Fees 
A random sample of...

Question 7

Concert Tickets A simple random sample of 100 concert tickets was drawn from a normal population.The mean and standard deviation of the sample were $120 and $25,respectively. -{Concert Tickets Narrative} Test the hypothesis H₀: μ = 125 vs.H₁: μ ≠ 125 at the 10% significance level.

Accepted Answer

The answer of  Concert Tickets 
A simple random sample...

Question 8

Single Mothers' Ages
 A random sample of 10 single mothers was drawn from a Obstetrics Clinic.Their ages are 22,17,27,20,23,19,24,18,19,and 24 years. ​ ​
-{Single Mothers' Ages Narrative} Estimate the population mean with 90% confidence.

Accepted Answer

The answer of Single Mothers' Ages
 A random sample of...

Question 9

The t-test for a population mean is ____________________,meaning that if the population is nonnormal,the results of the test and confidence interval are still valid as long as the nonnormality is not extreme.

Accepted Answer

The answer of The t-test for a population mean is...

Question 10

Single Mothers' Ages
 A random sample of 10 single mothers was drawn from a Obstetrics Clinic.Their ages are 22,17,27,20,23,19,24,18,19,and 24 years. ​ ​
-{Single Mothers' Ages Narrative} What is the required condition of the techniques used in the previous questions? What graphical device can you use to check to see if that required condition is satisfied?

Accepted Answer

The answer of Single Mothers' Ages
 A random sample of...

Question 11

The degrees of freedom for the test statistic for μ when σ is unknown is:
A)1
B)n
C)n − 1
D)None of these choices.

Accepted Answer

The degrees of freedom for the test statistic for μ when σ is unknown is equal to n-1. This is because when σ is unknown, the sample standard deviation s is used in place of σ and s itself is estimated from the sample. This estimation process reduces the degrees of freedom by 1, hence the degrees of freedom for the test statistic is n-1.

Question 12

Concert Tickets 
A simple random sample of 100 concert tickets was drawn from a normal population.The mean and standard deviation of the sample were $120 and $25,respectively. ​ ​
-{Concert Tickets Narrative} Estimate the population mean with 90% confidence.

Accepted Answer

The answer of  Concert Tickets 
A simple random sample...

Question 13

When the population standard deviation is unknown and the population is ____________________,the test statistic for testing hypotheses about μ is the t-distribution with n − 1 degrees of freedom.

Accepted Answer

The answer of When the population standard deviation is unknown...

Question 14

Hourly Fees 
A random sample of 15 hourly fees for car washers (including tips)was drawn from a normal population.The sample mean and sample standard deviation were  = $14.9 and s = $6.75. ​ ​
-{Hourly Fees Narrative} Can we infer at the 5% significance level that the population mean is greater than 12,assuming that you know the population standard deviation is equal to 6.75?

Accepted Answer

The answer of  Hourly Fees 
A random sample of...

Question 15

Researchers determined that 60 Puffs tissues is the average number of tissues used during a cold.Suppose a random sample of 100 Puffs users yielded the following data on the number of tissues used during a cold: = 52 and s = 22.Suppose the alternative we wanted to test was H₁: μ < 60.The correct rejection region for α = 0.05 is: A)reject H₀ if t > 1.6604. B)reject H₀ if t < −1.6604. C)reject H₀ if t > 1.9842 or Z < −1.9842. D)reject H₀ if t < −1.9842.

Accepted Answer

Since the alternative hypothesis is that the population mean is less than 60, we have a one-tailed test. For a one-tailed t-test with α = 0.05 and 99 degrees of freedom, the correct rejection region is t < -1.6604. Therefore, we reject the null hypothesis H₀ if t < -1.6604. Therefore, the best choice is option B.

Question 16

Concert Tickets 
A simple random sample of 100 concert tickets was drawn from a normal population.The mean and standard deviation of the sample were $120 and $25,respectively. ​ ​
-{Concert Tickets Narrative} Explain how to use the confidence interval to test the hypotheses at α = 0.10.

Accepted Answer

The answer of  Concert Tickets 
A simple random sample...

Question 17

When a population is small,we must adjust the test statistic and interval estimator using the ____________________ population correction factor.

Accepted Answer

The answer of When a population is small,we must adjust...

Question 18

Based on sample data,the 90% confidence interval limits for the population mean are LCL = 170.86 and UCL = 195.42.If the 10% level of significance were used in testing the hypotheses H₀: μ = 201 vs.H₁: μ ≠ 201,the null hypothesis: A)would be rejected. B)would be accepted. C)would fail to be rejected. D)would become H₀: μ ≠ 201

Accepted Answer

The null hypothesis would be rejected because the hypothesized mean (201) is not within the 90% confidence interval (170.86 to 195.42).

Question 19

When the population standard deviation is unknown and the population is normal,the test statistic for testing hypotheses about μ is the ____________________-distribution with ____________________ degrees of freedom.

Accepted Answer

The answer of When the population standard deviation is unknown...

Question 20

The t-statistic has two variables: the sample ____________________ and the sample ____________________.

Accepted Answer

The answer of The t-statistic has two variables: the sample...

Quiz 12: Inference About a Population

____________________ populations allow us to use the confidence interval estimate of a mean to produce a confidence interval estimate of the population total.

Because of the greater uncertainty,the t-statistic will display greater ____________________ than the z-statistic.

Single Mothers' Ages A random sample of 10 single mothers was drawn from a Obstetrics Clinic.Their ages are 22,17,27,20,23,19,24,18,19,and 24 years. -{Single Mothers' Ages Narrative} Test to determine if we can infer at the 5% significance level that the population mean is not equal to 20.

When the population standard deviation is ____________________ and the population is normal,the test statistic for testing hypotheses about μ is the t-distribution with n − 1 degrees of freedom.

Concert Tickets A simple random sample of 100 concert tickets was drawn from a normal population.The mean and standard deviation of the sample were $120 and $25,respectively. -{Concert Tickets Narrative} Test the hypothesis H₀: μ = 125 vs.H₁: μ ≠ 125 at the 10% significance level.

Single Mothers' Ages A random sample of 10 single mothers was drawn from a Obstetrics Clinic.Their ages are 22,17,27,20,23,19,24,18,19,and 24 years. -{Single Mothers' Ages Narrative} Estimate the population mean with 90% confidence.

The t-test for a population mean is ____________________,meaning that if the population is nonnormal,the results of the test and confidence interval are still valid as long as the nonnormality is not extreme.

The degrees of freedom for the test statistic for μ when σ is unknown is:

Concert Tickets A simple random sample of 100 concert tickets was drawn from a normal population.The mean and standard deviation of the sample were $120 and $25,respectively. -{Concert Tickets Narrative} Estimate the population mean with 90% confidence.

When the population standard deviation is unknown and the population is ____________________,the test statistic for testing hypotheses about μ is the t-distribution with n − 1 degrees of freedom.

Concert Tickets A simple random sample of 100 concert tickets was drawn from a normal population.The mean and standard deviation of the sample were $120 and $25,respectively. -{Concert Tickets Narrative} Explain how to use the confidence interval to test the hypotheses at α = 0.10.

When a population is small,we must adjust the test statistic and interval estimator using the ____________________ population correction factor.

Based on sample data,the 90% confidence interval limits for the population mean are LCL = 170.86 and UCL = 195.42.If the 10% level of significance were used in testing the hypotheses H₀: μ = 201 vs.H₁: μ ≠ 201,the null hypothesis:

When the population standard deviation is unknown and the population is normal,the test statistic for testing hypotheses about μ is the -distribution with degrees of freedom.

The t-statistic has two variables: the sample and the sample .

Quiz 12: Inference About a Population

____________________ populations allow us to use the confidence interval estimate of a mean to produce a confidence interval estimate of the population total.

Because of the greater uncertainty,the t-statistic will display greater ____________________ than the z-statistic.

Single Mothers' Ages A random sample of 10 single mothers was drawn from a Obstetrics Clinic.Their ages are 22,17,27,20,23,19,24,18,19,and 24 years. ​ ​ -{Single Mothers' Ages Narrative} Test to determine if we can infer at the 5% significance level that the population mean is not equal to 20.

When the population standard deviation is ____________________ and the population is normal,the test statistic for testing hypotheses about μ is the t-distribution with n − 1 degrees of freedom.

Concert Tickets A simple random sample of 100 concert tickets was drawn from a normal population.The mean and standard deviation of the sample were $120 and $25,respectively. ​ ​ -{Concert Tickets Narrative} Test the hypothesis H0: μ = 125 vs.H1: μ ≠ 125 at the 10% significance level.

Single Mothers' Ages A random sample of 10 single mothers was drawn from a Obstetrics Clinic.Their ages are 22,17,27,20,23,19,24,18,19,and 24 years. ​ ​ -{Single Mothers' Ages Narrative} Estimate the population mean with 90% confidence.

The t-test for a population mean is ____________________,meaning that if the population is nonnormal,the results of the test and confidence interval are still valid as long as the nonnormality is not extreme.

The degrees of freedom for the test statistic for μ when σ is unknown is:

Concert Tickets A simple random sample of 100 concert tickets was drawn from a normal population.The mean and standard deviation of the sample were $120 and $25,respectively. ​ ​ -{Concert Tickets Narrative} Estimate the population mean with 90% confidence.

When the population standard deviation is unknown and the population is ____________________,the test statistic for testing hypotheses about μ is the t-distribution with n − 1 degrees of freedom.

Concert Tickets A simple random sample of 100 concert tickets was drawn from a normal population.The mean and standard deviation of the sample were $120 and $25,respectively. ​ ​ -{Concert Tickets Narrative} Explain how to use the confidence interval to test the hypotheses at α = 0.10.

When a population is small,we must adjust the test statistic and interval estimator using the ____________________ population correction factor.

Based on sample data,the 90% confidence interval limits for the population mean are LCL = 170.86 and UCL = 195.42.If the 10% level of significance were used in testing the hypotheses H0: μ = 201 vs.H1: μ ≠ 201,the null hypothesis:

When the population standard deviation is unknown and the population is normal,the test statistic for testing hypotheses about μ is the ____________________-distribution with ____________________ degrees of freedom.

The t-statistic has two variables: the sample ____________________ and the sample ____________________.

Single Mothers' Ages A random sample of 10 single mothers was drawn from a Obstetrics Clinic.Their ages are 22,17,27,20,23,19,24,18,19,and 24 years. -{Single Mothers' Ages Narrative} Test to determine if we can infer at the 5% significance level that the population mean is not equal to 20.

Concert Tickets A simple random sample of 100 concert tickets was drawn from a normal population.The mean and standard deviation of the sample were $120 and $25,respectively. -{Concert Tickets Narrative} Test the hypothesis H₀: μ = 125 vs.H₁: μ ≠ 125 at the 10% significance level.

Single Mothers' Ages A random sample of 10 single mothers was drawn from a Obstetrics Clinic.Their ages are 22,17,27,20,23,19,24,18,19,and 24 years. -{Single Mothers' Ages Narrative} Estimate the population mean with 90% confidence.

Concert Tickets A simple random sample of 100 concert tickets was drawn from a normal population.The mean and standard deviation of the sample were $120 and $25,respectively. -{Concert Tickets Narrative} Estimate the population mean with 90% confidence.

Concert Tickets A simple random sample of 100 concert tickets was drawn from a normal population.The mean and standard deviation of the sample were $120 and $25,respectively. -{Concert Tickets Narrative} Explain how to use the confidence interval to test the hypotheses at α = 0.10.

Based on sample data,the 90% confidence interval limits for the population mean are LCL = 170.86 and UCL = 195.42.If the 10% level of significance were used in testing the hypotheses H₀: μ = 201 vs.H₁: μ ≠ 201,the null hypothesis:

When the population standard deviation is unknown and the population is normal,the test statistic for testing hypotheses about μ is the -distribution with degrees of freedom.

The t-statistic has two variables: the sample and the sample .