Stats quiz 4

The following information was obtained from matched samples taken from two populations. Assume the population of differences is normally distributed. Individual Method 1 Method 2 1 7 5 2 5 9 3 6 8 4 7 7 5 5 6 ​ The null hypothesis tested is H0: μd = 0. The test statistic for the difference between the two population means is

-1

The following information was obtained from matched samples taken from two populations. Assume the population of differences is normally distributed. Individual Method 1 Method 2 1 7 5 2 5 9 3 6 8 4 7 7 5 5 6 ​ The point estimate for the difference between the means of the two populations (Method 1 - Method 2) is

-1

A statistics teacher wants to see if there is any difference in the abilities of students enrolled in statistics today and those enrolled five years ago. A sample of final examination scores from students enrolled today and from students enrolled five years ago was taken. You are given the following information. Today Five Years Ago 82 88 σ2 112.5 54 n 45 36 ​ The test statistic for the difference between the two population means is

-3.0

The following information was obtained from matched samples taken from two populations. Assume the population of differences is normally distributed. Individual Method 1 Method 2 1 7 5 2 5 9 3 6 8 4 7 7 5 5 6 ​ The 95% confidence interval for the difference between the two population means is

-3.776 to 1.776

The following information was obtained from independent random samples taken of two populations.Assume normally distributed populations with equal variances. Sample 1 Sample 2 Sample Mean 45 42 Sample Variance 85 90 Sample Size 10 12 ​ The 95% confidence interval for the difference between the two population means is (use rounded standard error)

-5.344 to 11.344

A statistics teacher wants to see if there is any difference in the abilities of students enrolled in statistics today and those enrolled five years ago. A sample of final examination scores from students enrolled today and from students enrolled five years ago was taken. You are given the following information. Today Five Years Ago 82 88 σ2 112.5 54 n 45 36 ​ The point estimate for the difference between the means of the two populations is

-6

A statistics teacher wants to see if there is any difference in the abilities of students enrolled in statistics today and those enrolled five years ago. A sample of final examination scores from students enrolled today and from students enrolled five years ago was taken. You are given the following information. Today Five Years Ago 82 88 σ2 112.5 54 n 45 36 ​ The 95% confidence interval for the difference between the two population means is

-9.92 to -2.08

A statistics teacher wants to see if there is any difference in the abilities of students enrolled in statistics today and those enrolled five years ago. A sample of final examination scores from students enrolled today and from students enrolled five years ago was taken. You are given the following information. Today Five Years Ago 82 88 σ2 112.5 54 n 45 36 ​ The p-value for the difference between the two population means is

.0026

In order to determine whether or not there is a significant difference between the mean hourly wages paid by two companies (of the same industry), the following data have been accumulated. Company A Company B Sample size 80 60 Sample mean $16.75 $16.25 Population standard deviation $1.00 $.95 ​ The p-value is

.0026

Salary information regarding male and female employees of a large company is shown below. Male Female Sample Size 60 30 Sample Mean Salary (in $1000) 45 40 Population Variance () 120 70 ​ If you are interested in testing whether or not the population average salary of males is significantly greater than that of females, the p-value is

.0082

In order to estimate the difference between the average hourly wages of employees of two branches of a department store, the following data have been gathered. Downtown Store North Mall Store Sample size 25 20 Sample mean $9 $8 Sample standard deviation $2 $1 ​ A 95% interval estimate for the difference between the two population means is

.071 to 1.929

In order to determine whether or not there is a significant difference between the mean hourly wages paid by two companies (of the same industry), the following data have been accumulated. Company A Company B Sample size 80 60 Sample mean $16.75 $16.25 Population standard deviation $1.00 $.95 ​ A point estimate for the difference between the two population means is

.50

The following information was obtained from matched samples taken from two populations.The daily production rates for a sample of workers before and after a training program are shown below. Assume the population of differences is normally distributed. Worker Before After 1 20 22 2 25 23 3 27 27 4 23 20 5 22 25 6 20 19 7 17 18 ​ The null hypothesis to be tested is H0: μd = 0. The test statistic is

0

The following information was obtained from matched samples taken from two populations.The daily production rates for a sample of workers before and after a training program are shown below. Assume the population of differences is normally distributed. Worker Before After 1 20 22 2 25 23 3 27 27 4 23 20 5 22 25 6 20 19 7 17 18 ​ The point estimate for the difference between the means of the two populations is

0

Salary information regarding male and female employees of a large company is shown below. Male Female Sample Size 60 30 Sample Mean Salary (in $1000) 45 40 Population Variance () 120 70 ​ The 95% confidence interval for the difference between the means of the two populations is

0.92 to 9.08

In order to estimate the difference between the average hourly wages of employees of two branches of a department store, the following data have been gathered. Downtown Store North Mall Store Sample size 25 20 Sample mean $9 $8 Sample standard deviation $2 $1 ​ A point estimate for the difference between the two population means is

1

The management of a department store is interested in estimating the difference between the mean credit purchases of customers using the store's credit card versus those customers using a national major credit card. You are given the following information. Store's Card Major Credit Card Sample size 64 49 Sample mean $140 $125 Population standard deviation $10 $8 ​ A 95% confidence interval estimate for the difference between the average purchases of all customers using the two different credit cards is

11.68 to 18.32

The management of a department store is interested in estimating the difference between the mean credit purchases of customers using the store's credit card versus those customers using a national major credit card. You are given the following information. Store's Card Major Credit Card Sample size 64 49 Sample mean $140 $125 Population standard deviation $10 $8 ​ A point estimate for the difference between the mean purchases of all users of the two credit cards is

15

A statistics teacher wants to see if there is any difference in the abilities of students enrolled in statistics today and those enrolled five years ago. A sample of final examination scores from students enrolled today and from students enrolled five years ago was taken. You are given the following information. Today Five Years Ago 82 88 σ2 112.5 54 n 45 36 ​ The standard error of x1-x2 is

2

Salary information regarding male and female employees of a large company is shown below. Male Female Sample Size 60 30 Sample Mean Salary (in $1000) 45 40 Population Variance () 120 70 ​ The standard error of the difference between the two sample means is

2.08

Salary information regarding male and female employees of a large company is shown below. Male Female Sample Size 60 30 Sample Mean Salary (in $1000) 45 40 Population Variance () 120 70 ​ If you are interested in testing whether or not the population average salary of males is significantly greater than that of females, the test statistic is

2.40

The following information was obtained from independent random samples taken of two populations.Assume normally distributed populations with equal variances. Sample 1 Sample 2 Sample Mean 45 42 Sample Variance 85 90 Sample Size 10 12 ​ The degrees of freedom for the t distribution are

20

The following information was obtained from independent random samples taken of two populations.Assume normally distributed populations with equal variances. Sample 1 Sample 2 Sample Mean 45 42 Sample Variance 85 90 Sample Size 10 12 ​ The point estimate for the difference between the means of the two populations is

3

In order to determine whether or not there is a significant difference between the mean hourly wages paid by two companies (of the same industry), the following data have been accumulated. Company A Company B Sample size 80 60 Sample mean $16.75 $16.25 Population standard deviation $1.00 $.95 ​ The test statistic is

3.01

The management of a department store is interested in estimating the difference between the mean credit purchases of customers using the store's credit card versus those customers using a national major credit card. You are given the following information. Store's Card Major Credit Card Sample size 64 49 Sample mean $140 $125 Population standard deviation $10 $8 ​ At 95% confidence, the margin of error is

3.32

The following information was obtained from independent random samples taken of two populations.Assume normally distributed populations with equal variances. Sample 1 Sample 2 Sample Mean 45 42 Sample Variance 85 90 Sample Size 10 12 ​ The standard error of x1-x2 is

4

Salary information regarding male and female employees of a large company is shown below. Male Female Sample Size 60 30 Sample Mean Salary (in $1000) 45 40 Population Variance () 120 70 ​ At 95% confidence, the margin of error is

4.080

Salary information regarding male and female employees of a large company is shown below. Male Female Sample Size 60 30 Sample Mean Salary (in $1000) 45 40 Population Variance () 120 70 ​ The point estimate of the difference between the means of the two populations is

5

A statistics teacher wants to see if there is any difference in the abilities of students enrolled in statistics today and those enrolled five years ago. A sample of final examination scores from students enrolled today and from students enrolled five years ago was taken. You are given the following information. Today Five Years Ago 82 88 σ2 112.5 54 n 45 36 ​ What is the conclusion that can be reached about the difference in the average final examination scores between the two classes? (Use a .05 level of significance.)

There is a statistically significant difference in the average final examination scores between the two classes.

Salary information regarding male and female employees of a large company is shown below. Male Female Sample Size 60 30 Sample Mean Salary (in $1000) 45 40 Population Variance () 120 70 ​ If you are interested in testing whether or not the population average salary of males is significantly greater than that of females, at α = .05, the conclusion is that the population

average salary of males is greater than females cannot be proved.

The following information was obtained from matched samples taken from two populations. Assume the population of differences is normally distributed. Individual Method 1 Method 2 1 7 5 2 5 9 3 6 8 4 7 7 5 5 6 ​ If the null hypothesis H0: μd = 0 is tested at the 5% level,

he null hypothesis should not be rejected.

Of the two production methods, a company wants to identify the method with the smaller population mean completion time. One sample of workers is selected and each worker first uses one method and then uses the other method. The sampling procedure being used to collect completion time data is based on

matched samples

In order to determine whether or not there is a significant difference between the mean hourly wages paid by two companies (of the same industry), the following data have been accumulated. Company A Company B Sample size 80 60 Sample mean $16.75 $16.25 Population standard deviation $1.00 $.95 ​ At the 5% level of significance, the null hypothesis

should be rejected

The standard error of x1 - x2 is the

standard deviation of the sampling distribution of x1- x2.

The following information was obtained from matched samples taken from two populations.The daily production rates for a sample of workers before and after a training program are shown below. Assume the population of differences is normally distributed. Worker Before After 1 20 22 2 25 23 3 27 27 4 23 20 5 22 25 6 20 19 7 17 18 ​ Given that the null hypothesis to be tested is H0: μd = 0,

the null hypothesis should not be rejected.