STAT Chp 10

a. .0668

***Exhibit 10-1 Salary information regarding two independent random samples of male and female employees of a large company is shown below. Male Sample size: 64 Sample mean salary (in $1000s): 44 Population variance: 128 Female Sample size: 36 Sample mean salary (in $1000s): 41 Population variance: 72 Refer to Exhibit 10-1. The p-value is _____. a. 1.96 b. 1.336 c. .0334 d. .0668

a. pu - po = 0

***Exhibit 10-11 An insurance company selected samples of clients under 18 years of age and over 18 and recorded the number of accidents they had in the previous year. The results are shown below. Under Age 18 n1 = 500 Number of accidents = 180 Over Age 18 n2 = 600 Number of accidents = 150 We are interested in determining if the accident proportions differ between the two age groups. Refer to Exhibit 10-11 and let pu represent the proportion under and po the proportion over the age of 18. The null hypothesis is a. pu - po = o b. pu - po > (w line) 0 c. pu - po < (w line) 0 d. pu - po (does not) = 0

b. matched

A company wants to identify which of two production methods has the smaller completion time. One sample of workers is randomly 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 _____ samples. a. pooled b. matched c. cross d. independent

a. 3.96

An insurance company selected samples of clients under 18 years of age and over 18 and recorded the number of accidents they had in the previous year. The results are shown below. Under Age 18 n1 = 500 Number of accidents = 180 Over Age 18 n2 = 600 Number of accidents = 150 We are interested in determining if the accident proportions differ between the two age groups. Refer to Exhibit 10-11. The value of the test statistic is _____. a. 3.96 b. 1.96 c. 2.96 d. .96

b. 1.5

Exhibit 10-1 Salary information regarding two independent random samples of male and female employees of a large company is shown below. Male Sample size: 64 Sample mean salary (in $1000s): 44 Population variance: 128 Female Sample size: 36 Sample mean salary (in $1000s): 41 Population variance: 72 Refer to Exhibit 10-1. If you are interested in testing whether or not the average salary of males is significantly greater than that of females, the test statistic is a. 2.0 b. 1.5 c. 1.96 d. 1.645

d. 2.0

Exhibit 10-1 Salary information regarding two independent random samples of male and female employees of a large company is shown below. Male Sample size: 64 Sample mean salary (in $1000s): 44 Population variance: 128 Female Sample size: 36 Sample mean salary (in $1000s): 41 Population variance: 72 Refer to Exhibit 10-1. The standard error for the difference between the two means is a. 4 b. 7.46 c. 4.24 d. 2.0

b. 3.920

Exhibit 10-1 Salary information regarding two independent random samples of male and female employees of a large company is shown below. Male Sample size: 64 Sample mean salary (in $1000s): 44 Population variance: 128 Female Sample size: 36 Sample mean salary (in $1000s): 41 Population variance: 72 Refer to Exhibit 10-1. At 95% confidence, the margin of error is _____. a. 1.645 b. 3.920 c. 2.000 d. 1.96

a. none of the answers is correct

Exhibit 10-1 Salary information regarding two independent random samples of male and female employees of a large company is shown below. Male Sample size: 64 Sample mean salary (in $1000s): 44 Population variance: 128 Female Sample size: 36 Sample mean salary (in $1000s): 41 Population variance: 72 Refer to Exhibit 10-1. At 95% confidence, we have enough evidence to conclude that the _____. a. none of the answers is correct b. salaries of males and females are equal c. average salary of males is significantly greater than females d. average salary of males is significantly lower than females

a. 3

Exhibit 10-1 Salary information regarding two independent random samples of male and female employees of a large company is shown below. Male Sample size: 64 Sample mean salary (in $1000s): 44 Population variance: 128 Female Sample size: 36 Sample mean salary (in $1000s): 41 Population variance: 72 Refer to Exhibit 10-1. The point estimate of the difference between the means of the two populations (Male - Female) is _____. a. 3 b. 4 c. -4 d. -28

d. -.92 to 6.92

Exhibit 10-1 Salary information regarding two independent random samples of male and female employees of a large company is shown below. Male Sample size: 64 Sample mean salary (in $1000s): 44 Population variance: 128 Female Sample size: 36 Sample mean salary (in $1000s): 41 Population variance: 72 Refer to Exhibit 10-1. The 95% confidence interval for the difference between the means of the two populations is _____. a. -1.96 to 1.96 b. 0 to 6.92 c. -2 to 2 d. -.92 to 6.92

b. 0.044

Exhibit 10-10 The results of a recent poll on the preference of shoppers regarding two products are shown below. Product A Shoppers Surveyed: 800 Shoppers Favoring this Product: 560 Product B Shoppers Surveyed: 900 Shopper Favoring this Product: 612 Refer to Exhibit 10-10. At 95% confidence, the margin of error is a. 0.064 b. 0.044 c. 0.0225 d. 52

c. 0.0225

Exhibit 10-10 The results of a recent poll on the preference of shoppers regarding two products are shown below. Product A Shoppers Surveyed: 800 Shoppers Favoring this Product: 560 Product B Shoppers Surveyed: 900 Shopper Favoring this Product: 612 Refer to Exhibit 10-10. The standard error of SOMETHING is a. 52 b. 0.044 c. 0.0225 d. 100

a. 52

Exhibit 10-10 The results of a recent poll on the preference of shoppers regarding two products are shown below. Product A Shoppers Surveyed: 800 Shoppers Favoring this Product: 560 Product B Shoppers Surveyed: 900 Shopper Favoring this Product: 612 Refer to Exhibit 10-10. The standard error of pbar1-pbar2 is _____. a. 52 b. 100 c. .044 d. .0225

c. -.024 to .064

Exhibit 10-10 The results of a recent poll on the preference of shoppers regarding two products are shown below. Product A Shoppers Surveyed: 800 Shoppers Favoring this Product: 560 Product B Shoppers Surveyed: 900 Shopper Favoring this Product: 612 Refer to Exhibit 10-10. The 95% confidence interval estimate for the difference between the populations favoring the products is _____. a. .6 to .7 b. .024 to .7 c. -.024 to .064 d. .02 to .3

b. .02

Exhibit 10-10 The results of a recent poll on the preference of shoppers regarding two products are shown below. Product A Shoppers Surveyed: 800 Shoppers Favoring this Product: 560 Product B Shoppers Surveyed: 900 Shopper Favoring this Product: 612 Refer to Exhibit 10-10. The point estimate for the difference between the two population proportions in favor of this product (Product A - Product B) is _____. a. .44 b. .02 c. 100 d. 52

c. .300

Exhibit 10-11 An insurance company selected samples of clients under 18 years of age and over 18 and recorded the number of accidents they had in the previous year. The results are shown below. Under Age 18 n1 = 500 Number of accidents = 180 Over Age 18 n2 = 600 Number of accidents = 150 Refer to Exhibit 10-11. The pooled proportion is _____. a. .305 b. .027 c. .300 d. .450

c. less than .001

Exhibit 10-11 An insurance company selected samples of clients under 18 years of age and over 18 and recorded the number of accidents they had in the previous year. The results are shown below. Under Age 18 n1 = 500 Number of accidents = 180 Over Age 18 n2 = 600 Number of accidents = 150 We are interested in determining if the accident proportions differ between the two age groups. Refer to Exhibit 10-11. The p-value is _____. a. more than .10 b. .3 c. less than .001 d. .0228

b. -.02

Exhibit 10-12 The results of a recent poll on the preference of teenagers regarding the types of music they listen to are shown below. Music Type: Pop Teenagers Surveyed: 800 Teenagers Favoring This Type: 384 Music Type: Rap Teenagers Surveyed: 900 Teenagers Favoring: 450 Refer to Exhibit 10-12. The point estimate for the difference between the proportions is _____. a. 66 b. -.02 c. .048 d. 100

d. 0.0243

Exhibit 10-12 The results of a recent poll on the preference of teenagers regarding the types of music they listen to are shown below. Music Type: Pop Teenagers Surveyed: 800 Teenagers Favoring This Type: 384 Music Type: Rap Teenagers Surveyed: 900 Teenagers Favoring: 450 Refer to Exhibit 10-12. The standard error of SOMETHING is a. 0.48 b. 0.50 c. 0.03 d. 0.0243

d. -.068 to .028

Exhibit 10-12 The results of a recent poll on the preference of teenagers regarding the types of music they listen to are shown below. Music Type: Pop Teenagers Surveyed: 800 Teenagers Favoring This Type: 384 Music Type: Rap Teenagers Surveyed: 900 Teenagers Favoring: 450 Refer to Exhibit 10-12. The 95% confidence interval for the difference between the two proportions is _____. a. .48 to .5 b. .028 to .068 c. 384 to 450 d. -.068 to .028

c. u1-u2 = 0

Exhibit 10-13 In order to determine whether or not there is a significant difference between the hourly wages of two companies, the following data have been accumulated. Company 1 n1 = 80 x1 = $10.80 σ1= $2.00 Company 2 n2 = 60 x2 = $10.00 σ2 = $1.50 Refer to Exhibit 10-13. The null hypothesis for this test is _____. a. u1-u2 does not = 0 b. u1-u2 > (w line) 0 c. u1-u2 = 0 d. u1-u2 < (w line) 0

d. 2.7

Exhibit 10-13 In order to determine whether or not there is a significant difference between the hourly wages of two companies, the following data have been accumulated. Company 1 n1 = 80 x1 = $10.80 σ1= $2.00 Company 2 n2 = 60 x2 = $10.00 σ2 = $1.50 Refer to Exhibit 10-13. The test statistic has a value of ______. a. .80 b. 1.645 c. 1.96 d. 2.7

d. .007

Exhibit 10-13 In order to determine whether or not there is a significant difference between the hourly wages of two companies, the following data have been accumulated. Company 1 n1 = 80 x1 = $10.80 σ1= $2.00 Company 2 n2 = 60 x2 = $10.00 σ2 = $1.50 Refer to Exhibit 10-13. The p-value is _____. a. .4965 b. .0035 c. 1.96 d. .007

a. .8

Exhibit 10-13 In order to determine whether or not there is a significant difference between the hourly wages of two companies, the following data have been accumulated. Company 1 n1 = 80 x1 = $10.80 σ1= $2.00 Company 2 n2 = 60 x2 = $10.00 σ2 = $1.50 Refer to Exhibit 10-13. The point estimate of the difference between the means (Company 1 - Company 2) is _____. a. .8 b. .50 c. 20 d. -20

d. null hypothesis should not be rejected

Exhibit 10-2 The following information was obtained from matched samples. The daily production rates for a random sample of workers before and after a training program are shown below. Worker Before After 1 20 22 2 25 23 3 27 27 4 23 20 5 22 25 6 20 19 7 17 18 Refer to Exhibit 10-2. Based on the results of the previous question, the _____. a. alternative hypothesis should be accepted b. null hypothesis should be rejected c. none of the answers is correct d. null hypothesis should not be rejected

b. 0

Exhibit 10-2 The following information was obtained from matched samples. The daily production rates for a random sample of workers before and after a training program are shown below. Worker Before After 1 20 22 2 25 23 3 27 27 4 23 20 5 22 25 6 20 19 7 17 18 Refer to Exhibit 10-2. The null hypothesis to be tested is H0: μd = 0. The value of the test statistic is _____. a. -1.96 b. 0 c. 1.96 d. 1.645

c. 0

Exhibit 10-2 The following information was obtained from matched samples. The daily production rates for a random sample of workers before and after a training program are shown below. Worker Before After 1 20 22 2 25 23 3 27 27 4 23 20 5 22 25 6 20 19 7 17 18 Refer to Exhibit 10-2. The point estimate for the difference between the means of the two populations is a. -1 b. -2 c. 0 d. 1

b. -9.92 to -2.08

Exhibit 10-3 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. Final examination scores from a random sample of students enrolled today and from a random sample of students enrolled five years ago were selected. You are given the following information. Today xbar: 82 σ^2: 112.5 n: 45 Five Years Ago xbar: 88 σ^2: 54 n: 36 Refer to Exhibit 10-3. The 95% confidence interval for the difference between the two population means is _____. a. -13.84 to 1.84 b. -9.92 to -2.08 c. -24.228 to 12.23 d. -3.92 to 3.92

b. .0026

Exhibit 10-3 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. Final examination scores from a random sample of students enrolled today and from a random sample of students enrolled five years ago were selected. You are given the following information. Today xbar: 82 σ^2: 112.5 n: 45 Five Years Ago xbar: 88 σ^2: 54 n: 36 Refer to Exhibit 10-3. The p-value for the difference between the two populations means is a. .0013 b. .0026 c. .4987 d. .9987

d. -6

Exhibit 10-3 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. Final examination scores from a random sample of students enrolled today and from a random sample of students enrolled five years ago were selected. You are given the following information. Today xbar: 82 σ^2: 112.5 n: 45 Five Years Ago xbar: 88 σ^2: 54 n: 36 Refer to Exhibit 10-3. The point estimate for the difference between the means of the two populations is a. 58.5 b. 9 c. -9 d. -6

b. 2

Exhibit 10-3 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. Final examination scores from a random sample of students enrolled today and from a random sample of students enrolled five years ago were selected. You are given the following information. Today xbar: 82 σ^2: 112.5 n: 45 Five Years Ago xbar: 88 σ^2: 54 n: 36 Refer to Exhibit 10-3. The standard error of xbar1-xbar2 is _____ a. 4 b. 2 c. 12.9 d. 9.3

a. -3

Exhibit 10-3 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. Final examination scores from a random sample of students enrolled today and from a random sample of students enrolled five years ago were selected. You are given the following information. Today xbar: 82 σ^2: 112.5 n: 45 Five Years Ago xbar: 88 σ^2: 54 n: 36 Refer to Exhibit 10-3. The test statistic for the difference between the two population means is _____. a. -3 b. -1.5 c. -.47 d. -.65

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

Exhibit 10-3 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. Final examination scores from a random sample of students enrolled today and from a random sample of students enrolled five years ago were selected. You are given the following information. Today xbar: 82 σ^2: 112.5 n: 45 Five Years Ago xbar: 88 σ^2: 54 n: 36 Refer to Exhibit 10-3. What is the conclusion that can be reached about the difference in the average of final exam scores between the two classes? (Use a .05 level of significance) a. There is a statistically significant difference in the average final exam scores between the two classes b. There is no statistically significant difference in the average final exam scores between the two classes c. It is impossible to make a decision on the basis of the information given d. There is a difference, but it is not significant.

c. 20

Exhibit 10-4 The following information was obtained from independent random samples. Assume normally distributed populations with equal variances. Sample 1 sample mean: 45 sample variance: 85 sample size: 10 Sample 2 sample mean: 42 sample variance: 90 sample size: 12 Refer to Exhibit 10-4. The degrees of freedom for the t-distriubiotn are a. 21 b. 19 c. 20 d. 22

C. 3

Exhibit 10-4 The following information was obtained from independent random samples. Assume normally distributed populations with equal variances. Sample 1 sample mean: 45 sample variance: 85 sample size: 10 Sample 2 sample mean: 42 sample variance: 90 sample size: 12 Refer to Exhibit 10-4. The point estimate for the difference between the means of the two populations is a. 0 b. 2 c. 3 d. 15

d. 4.0

Exhibit 10-4 The following information was obtained from independent random samples. Assume normally distributed populations with equal variances. Sample 1 sample mean: 45 sample variance: 85 sample size: 10 Sample 2 sample mean: 42 sample variance: 90 sample size: 12 Refer to Exhibit 10-4. The standard error of xbar1-xbar2 is _____. a. 3.0 b. 19.48 c. 8.372 d. 4.0

d. -5.37 to 11.367

Exhibit 10-4 The following information was obtained from independent random samples. Assume normally distributed populations with equal variances. Sample 1 sample mean: 45 sample variance: 85 sample size: 10 Sample 2 sample mean: 42 sample variance: 90 sample size: 12 Refer to Exhibit 10-4. The 95% confidence interval for the difference between the two population means is _____. a. -5 to 3 b. -2.65 to 8.65 c. -4.86 to 10.86 d. -5.367 to 11.367

a. should not be rejected

Exhibit 10-5 The following information was obtained from matched samples. Individual Method 1 Method 2 1 7 5 2 5 9 3 6 8 4 7 7 5 5 6 Refer to Exhibit 10-5. If the null hypothesis is tested at the 5% level, the null hypothesis _____. a. should not be rejected b. should be rejected c. none of the answers is correct d. should be revised

c. -3.776 to 1.776

Exhibit 10-5 The following information was obtained from matched samples. Individual Method 1 Method 2 1 7 5 2 5 9 3 6 8 4 7 7 5 5 6 Refer to Exhibit 10-5. The 95% confidence interval for the mean of the population of differences is _____. a. -1.776 to 2.776 b. 0 to 3.776 c. -3.776 to 1.776 d. -2.776 to 2.776

c. -1

Exhibit 10-5 The following information was obtained from matched samples. Individual Method 1 Method 2 1 7 5 2 5 9 3 6 8 4 7 7 5 5 6 Refer to Exhibit 10-5. The null hypothesis tested is H0: d = 0. The test statistic for the difference between the two population means is a. 2 b. 0 c. -1 d. -2

a. -1

Exhibit 10-5 The following information was obtained from matched samples. Individual Method 1 Method 2 1 7 5 2 5 9 3 6 8 4 7 7 5 5 6 Refer to Exhibit 10-5. The point estimate for the difference between the means of the two populations (Method 1 - Method 2) is a. -1 b. 0 c. -4 d. 2

a. 11.68 to 18.32

Exhibit 10-6 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. Assume the samples were selected randomly. Store's Card Sample size: 64 Sample mean: $140 Population standard deviation: $10 Major Credit Card Sample size: 49 Sample mean: $125 Population standard deviation: $8 Refer to Exhibit 10-6. A 95% confidence interval estimate for the difference (Store's Card - Major Credit Card) between the average purchases of the customers using the two different credit cards is _____. a. 11.68 to 18.32 b. 125 to 140 c. 8 to 10 d. 49 to 64

b. 15

Exhibit 10-6 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. Assume the samples were selected randomly. Store's Card Sample size: 64 Sample mean: $140 Population standard deviation: $10 Major Credit Card Sample size: 49 Sample mean: $125 Population standard deviation: $8 Refer to Exhibit 10-6. A point estimate for the difference between the mean purchases of the users of the two credit cards (Store's Card - Major Credit Card) is _____. a. 265 b. 15 c. 18 d. 2

b. 3.32

Exhibit 10-6 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. Assume the samples were selected randomly. Store's Card Sample size: 64 Sample mean: $140 Population standard deviation: $10 Major Credit Card Sample size: 49 Sample mean: $125 Population standard deviation: $8 Refer to Exhibit 10-6. At 95% confidence, the margin of error is a. 1.694 b. 3.32 c. 1.96 d. 15

a. 0.078 to 1.922

Exhibit 10-7 In order to estimate the difference between the average hourly wages of employees of two branches of a department store, two independent random samples were selected and the following statistics were calculated. Downtown Store Sample size: 25 Sample mean: $9 Sample standard deviation: $2 North Mall Store Sample size: 20 Sample mean: $8 Sample standard deviation: $1 Refer to Exhibit 10-7. A 95% interval estimare for the difference between the two population means is a. 0.078 to 1.922 b. 1.922 to 2.078 c. 1.09 to 4.078 d. 1.078 to 2.922

b. 1

Exhibit 10-7 In order to estimate the difference between the average hourly wages of employees of two branches of a department store, two independent random samples were selected and the following statistics were calculated. Downtown Store Sample size: 25 Sample mean: $9 Sample standard deviation: $2 North Mall Store Sample size: 20 Sample mean: $8 Sample standard deviation: $1 Refer to Exhibit 10-7. A point estimate for the difference between the two sample means (Downtown Store - North Mall Store) is _____. a. 3 b. 1 c. 4 d. 2

c. .50

Exhibit 10-8 In order to determine whether or not there is a significant difference between the hourly wages of two companies, two independent random samples were selected and the following statistics were calculated. Company A Sample size: 80 Sample mean: $6.75 Population standard deviation: $1.00 Company B Sample size: 60 Sample mean: $6.25 Population standard deviation: $0.95 Refer to Exhibit 10-8. A point estimate for the difference between the two sample means (Company A - Company B) is _____ a. 1.00 b. .25 c. .50 d. 20

a. should be rejected

Exhibit 10-8 In order to determine whether or not there is a significant difference between the hourly wages of two companies, two independent random samples were selected and the following statistics were calculated. Company A Sample size: 80 Sample mean: $6.75 Population standard deviation: $1.00 Company B Sample size: 60 Sample mean: $6.25 Population standard deviation: $0.95 Refer to Exhibit 10-8. The null hypothesis a. should be rejected b. should not be rejected c. should be revised d. none of these alternatives is correct

a. .0026

Exhibit 10-8 In order to determine whether or not there is a significant difference between the hourly wages of two companies, two independent random samples were selected and the following statistics were calculated. Company A Sample size: 80 Sample mean: $6.75 Population standard deviation: $1.00 Company B Sample size: 60 Sample mean: $6.25 Population standard deviation: $0.95 Refer to Exhibit 10-8. The p-value is _____. a. .0026 b. .0084 c. .0013 d. .0042

d. 3.01

Exhibit 10-8 In order to determine whether or not there is a significant difference between the hourly wages of two companies, two independent random samples were selected and the following statistics were calculated. Company A Sample size: 80 Sample mean: $6.75 Population standard deviation: $1.00 Company B Sample size: 60 Sample mean: $6.25 Population standard deviation: $0.95 Refer to Exhibit 10-8. The value of the test statistic is _____. a. 2.75 b. 1.645 c. .098 d. 3.01

b. should be rejected

Exhibit 10-9 Two major automobile manufacturers have produced compact cars with the same size engines. We are interested in determining whether or not there is a significant difference in the MPG (miles per gallon) of the two brands of automobiles. A random sample of eight cars from each manufacturer is selected, and eight drivers are selected to drive each automobile for a specified distance. The following data show the results of the test. Driver Manufacturer A Manufacturer B 1 32 28 2 27 22 3 26 27 4 26 24 5 25 24 6 29 25 7 31 28 8 25 27 Refer to Exhibit 10-9. At 90% confidence the null hypothesis a. should not be rejected b. should be rejected c. should be revised d. none of these alternatives is correct

b. 2.0

Exhibit 10-9 Two major automobile manufacturers have produced compact cars with the same size engines. We are interested in determining whether or not there is a significant difference in the MPG (miles per gallon) of the two brands of automobiles. A random sample of eight cars from each manufacturer is selected, and eight drivers are selected to drive each automobile for a specified distance. The following data show the results of the test. Driver Manufacturer A Manufacturer B 1 32 28 2 27 22 3 26 27 4 26 24 5 25 24 6 29 25 7 31 28 8 25 27 Refer to Exhibit 10-9. The mean of the differences (Manufacturer A - Manufacturer B) is _____. a. 1.5 b. 2.0 c. .50 d. 2.5

d. 2.256

Exhibit 10-9 Two major automobile manufacturers have produced compact cars with the same size engines. We are interested in determining whether or not there is a significant difference in the MPG (miles per gallon) of the two brands of automobiles. A random sample of eight cars from each manufacturer is selected, and eight drivers are selected to drive each automobile for a specified distance. The following data show the results of the test. Driver Manufacturer A Manufacturer B 1 32 28 2 27 22 3 26 27 4 26 24 5 25 24 6 29 25 7 31 28 8 25 27 Refer to Exhibit 10-9. The test statistic is a. 1.645 b. 1.96 c. 2.096 d. 2.256

d. p1-p2 ≤ 0

If the alternative hypothesis is that proportion of items in population 1 is larger than the proportion of items in population 2, then the null hypothesis should be _____. a. p1-p2 < 0 b. p1-p2 = 0 c. p1-p2 > 0 d. p1-p2 ≤ 0

d. can be approximated by a normal distribution

If two independent large samples are selected from two populations, the smiling distribution of the difference between the two sample means _______ a. can be approximated by a Poisson distribution b. will have a mean of 1 c. will have a variance of 1 d. can be approximated by a normal distribution

c. alternative hypothesis should state p1 - p2 > 0

If we are interested in testing whether the proportion of items in population 1 is larger than the proportion of items in population 2, the a. null hypothesis should state p1 - p2 < 0 b. null hypothesis should state p1 - p2 > 0 c. alternative hypothesis should state p1 - p2 > 0 d. alternative hypothesis should state p1 - p2 < 0

a. .0485

In testing the null hypothesis H0: μ1 - μ2 = 0, the computed test statistic is z = -1.66. The corresponding p-value is _____. a. .0485 b. .9030 c. .9515 d. .0970

d. the correct degrees of freedom cannot be calculated without being given the sample standard deviations

Independent simple random samples are selected to test the difference between the means of two populations whose standard deviations are not known. We are unwilling to assume that the population variances are equal. The sample sizes are n1 = 25 and n2 = 35. The correct distribution to use is the t distribution with ______ degrees of freedom. a. 25 b. 35 c. 58 d. the correct degrees of freedom cannot be calculated without being given the sample standard deviations

c. t

Independent simple random samples are selected to test the difference between the means of two populations whose variances are not known. The sample sizes are n1 = 32 and n2 = 40. The correct distribution to use is the _____ distribution. a. uniform b. normal c. t d. binomial

d. t distribution with 58 degrees of freedom

Independent simple random samples are taken to test the difference between the means of two populations whose standard deviations are not known, but are assumed to be equal. The sample sizes are n1 = 25 and n2 = 35. The correct distribution to use is the a. t distribution with 61 degrees of freedom b. t distribution with 60 degrees of freedom c. t distribution with 59 degrees of freedom d. t distribution with 58 degrees of freedom

d. t distribution with 70 degrees of freedom

Independent simple random samples are taken to test the difference between the means of two populations whose variances are not known, but are assumed to be equal. The sample sizes are n1 = 32 and n2 = 40. The correct distribution to use is the a. t distribution with 73 degrees of freedom b. t distribution with 72 degrees of freedom c. t distribution with 71 degrees of freedom d. t distribution with 70 degrees of freedom

a. normal distribution

The sampling distribution of pbar1 - pbar2 is approximated by a _______ a. normal distribution b. t distribution with n1+n2 degrees of freedom c. t distribution with n1+n2+2 degrees of freedom d. t distribution with n1+n2-1 degrees of freedom

a. is not restricted to small sample situations

To compute an interval estimate for the difference between the means of two populations, the t distribution _____. a. is not restricted to small sample situations b. none of the answers is correct c. can be applied when the populations have equal means d. is restricted to small sample situations

c. (n1+n2-2)

To construct an interval estimate for the difference between the means of two populations when the standard deviations of the two populations are unknown and it can be assumed the two populations have equal variances, we must use a t distribution with (let n1 be the size of sample 1 and n2 the size of sample 2) a. (n1+n2) degrees of freedom b. (n1+n2-1) degrees of freedom c. (n1+n2-2) degrees of freedom d. (n1-n2+2) degrees of freedom

b. n1 and n2 can be different sizes

When developing an interval estimate for the difference between two sample means, with sample sizes of n1 and n2, _____. a. n1 must be larger than n2 b. n1 and n2 can be of different sizes c. n1 must be equal to n2 d. n1 must be smaller than n2

b. matched samples

When each data value in one sample is matched with a corresponding data value in another sample, the samples are known as _____. a. none of the answers is correct b. matched samples c. independent samples d. corresponding samples

a. standard deviation of the sampling distribution of xbar1-xbar2

the standard error of xbar1-xbar2 is the _____ a. standard deviation of the sampling distribution of xbar1-xbar2 b. variance of xbar1-xbar2 c. difference between the two means d. variance of the sampling distribution of xbar1-xbar2