Business Statistics: Part III: Inference for Decision Making – Test A
Name___________________________________________________
Chapter 10: Write null and alternative hypotheses.
1. A truck company wants on-time delivery for 98% of the parts they order from a metal
manufacturing plant. They have been ordering from Hudson Manufacturing but will
switch to a new, cheaper manufacturer (Steel-R-Us) unless there is evidence that this
new manufacturer cannot meet the 98% on-time goal. As a test the truck company
purchases a random sample of metal parts from Steel-R-Us, and then determines if
these parts were delivered on-time. Which hypotheses should they test?
H 0 : p < 0.98
A.
H a : p > 0.98
H 0 : p > 0.98
B.
H a : p = 0.98
H 0 : p = 0.98
C.
H a : p < 0.98
H 0 : p = 0.98
D.
H a : p ≠ 0.98
H 0 : p = 0.98
E.
H a : p > 0.98
Chapter 11: Perform hypothesis tests for means.
2. The weights of soy patties sold by Veggie Burgers Delight are normally distributed. A
random sample of 15 patties yields a mean weight of 3.8 ounces with a sample standard
deviation of 0.5 ounces. At the 0.05 level of significance, perform a hypothesis test to
see if the true mean weight is less than 4 ounces.
The correct null and alternative hypotheses are
A. H0 : µ = 4; HA : µ > 4
B. H0 : µ = 4; HA : µ < 4
C. H0 : µ > 4; HA : µ = 4
D. H0 : µ < 4; HA : µ = 4
E. H0 : µ = 4; HA : µ ≠ 4
IIIA-1
Copyright © 2015 Pearson Education, Inc.
,IIIA-2 Part III: Inference for Decision Making
Chapter 11: Perform hypothesis tests for means.
3. The weights of soy patties sold by Veggie Burgers Delight are normally distributed. A
random sample of 15 patties yields a mean weight of 3.8 ounces with a sample standard
deviation of 0.5 ounces. At the .05 level of significance, perform a hypothesis test to see
if the true mean weight is less than 4 ounces.
The correct calculated value of the test statistic is
A. -0.4
B. 0.4
C. -1.55
D. 1.55
E. 2.79
Chapter 13: Investigate and interpret P‐values in the context of t‐tests.
4. A sample of 30 year fixed mortgage rates at 12 randomly chosen credit unions yields a
mean rate of 6.65 % and a sample standard deviation of 0.38%. A sample of 30 year
fixed mortgage rates at 16 randomly selected banks yields a mean rate of 7.05% and a
sample standard deviation of 0.22%. Are the mean rates different between credit unions
and banks? Relevant output is shown below. At the 0.05 level of significance, the
correct conclusion is
Two-Sample T-Test and CI
Sample N Mean StDev SE Mean
1 12 6.650 0.390 0.11
2 16 7.050 0.220 0.055
Difference = mu (1) - mu (2)
Estimate for difference: -0.400
95% CI for difference: (-0.666, -0.134)
T-Test of difference = 0 (vs not =): T-Value = -3.19 P-Value = 0.006 DF = 16
A. Reject the null hypothesis.
B. Do not reject the null hypothesis.
C. Evidence suggests that there is a significant difference in mean mortgage rates
between credit unions and banks.
D. Both A and C.
E. Both B and C.
Chapter 12: Interpret and understand P‐values and alpha levels.
5. A P-value indicates
A. the probability that the null hypothesis is true.
B. the probability that the alternative hypothesis is true.
C. the probability of the observed statistic given that the null hypothesis is true.
D. the probability of the observed statistic given that the alternative hypothesis is
true.
E. None of the above.
Copyright © 2015 Pearson Education, Inc.
, Test A IIIA-3
Chapter 13: Investigate and interpret P‐values in the context of t‐tests.
6. A professor was interested in determining whether the prices of new textbooks in the
bookstore were higher than if purchased online. She selected 6 textbooks and priced each
at the bookstore and online.
Paired T for Bookstore - Online
N Mean StDev SE Mean
Bookstore 6 115.00 22.36 9.13
Online 6 105.83 13.20 5.39
Difference 6 9.17 13.20 5.39
95% lower bound for mean difference: -1.69
T-Test of mean difference = 0 (vs > 0): T-Value = 1.70 P-Value = 0.075
Based on her analysis, we can conclude at the 0.05 level of significance that
A. The prices are the same in the bookstore and online.
B. The prices are higher in the bookstore.
C. The prices are higher online.
D. The prices are different in the bookstore and online.
E. The analysis is not conclusive.
Chapter 12: Identify and understand Type I errors, Type II errors, and the power of a test.
7. Absorption rates into the body are important considerations when manufacturing a
generic version of a brand-name drug. A pharmacist read that the absorption rate into
the body of a new generic drug (G) is the same as its brand-name counterpart (B). She
has a researcher friend of hers run a small experiment to test H 0 : μG − μ B = 0 against the
alternative H A : μG − μ B ≠ 0 . Which of the following would be a Type I error?
A. Deciding that the absorption rates are the same, when in fact they are.
B. Deciding that the absorption rates are different, when in fact they are.
C. Deciding that the absorption rates are the same, when in fact they are not.
D. Deciding that the absorption rates are different, when in fact they are not.
E. The researcher cannot make a Type I error, since he has run an experiment.
Chapter 11: Create and interpret confidence intervals for the mean.
8. We have created a 95% confidence interval for µ with the result (10, 15). What
conclusion will we make if we test H 0 : µ = 16 versus HA : µ ≠ 16 at α = 0.05?
A. Reject the null hypothesis
B. Accept the null hypothesis
C. Fail to reject the null hypothesis.
D. Reject the alternative hypothesis.
E. No decision can be made from the information given.
Copyright © 2015 Pearson Education, Inc.
, IIIA-4 Part III: Inference for Decision Making
Chapter 10: Understand errors in hypothesis tests.
9. Suppose that a manufacturer is testing one of its machines to make sure that the
machine is producing more than 97% good parts ( H 0 : p = 0.97 and H A : p > 0.97 ) .
The test results in a P-value of 0.102. In reality, the machine is producing 99% good
parts. What probably happens as a result of our testing?
A. We correctly fail to reject H 0 .
B. We correctly reject H 0 .
C. We reject H 0 , making a Type I error.
D. We fail to reject H 0 , making a Type I error.
E. We fail to reject H 0 , making a Type II error.
Chapter 11: Perform hypothesis tests for means.
10. The weights of soy patties sold by Veggie Burgers Delight are normally distributed.
A random sample of 15 patties yields a mean weight of 3.8 ounces with a sample
standard deviation of 0.5 ounces. At the 0.05 level of significance, perform a hypothesis
test to see if the true mean weight is less than 4 ounces.
The correct conclusion at the 0.05 level of significance is
A. Do not reject the null hypothesis.
B. Reject the null hypothesis.
C. Evidence suggests that the mean weight is less than 4 ounces.
D. Both A and C.
E. Both B and C.
Chapter 13: Determine whether two samples are independent or paired.
11. A sample of 30 year fixed mortgage rates at 12 randomly chosen credit unions yields
a mean rate of 6.65 % and a sample standard deviation of 0.38%. A sample of 30 year
fixed mortgage rates at 16 randomly selected banks yields a mean rate of 7.05% and a
sample standard deviation of 0.22%. Are the mean rates different between credit unions
and banks? Relevant output is shown below. Which of the following is true?
Sample N Mean StDev SE Mean
1 12 6.650 0.390 0.11
2 16 7.050 0.220 0.055
Difference = mu (1) - mu (2)
Estimate for difference: -0.400
95% CI for difference: (-0.666, -0.134)
T-Test of difference = 0 (vs not =): T-Value = -3.19 P-Value = 0.006 DF = 16
A. This is a paired design.
B. This is a test of two means from independent samples.
C. This is a one tailed test.
D. Both A and C.
E. Both B and C.
Copyright © 2015 Pearson Education, Inc.
Name___________________________________________________
Chapter 10: Write null and alternative hypotheses.
1. A truck company wants on-time delivery for 98% of the parts they order from a metal
manufacturing plant. They have been ordering from Hudson Manufacturing but will
switch to a new, cheaper manufacturer (Steel-R-Us) unless there is evidence that this
new manufacturer cannot meet the 98% on-time goal. As a test the truck company
purchases a random sample of metal parts from Steel-R-Us, and then determines if
these parts were delivered on-time. Which hypotheses should they test?
H 0 : p < 0.98
A.
H a : p > 0.98
H 0 : p > 0.98
B.
H a : p = 0.98
H 0 : p = 0.98
C.
H a : p < 0.98
H 0 : p = 0.98
D.
H a : p ≠ 0.98
H 0 : p = 0.98
E.
H a : p > 0.98
Chapter 11: Perform hypothesis tests for means.
2. The weights of soy patties sold by Veggie Burgers Delight are normally distributed. A
random sample of 15 patties yields a mean weight of 3.8 ounces with a sample standard
deviation of 0.5 ounces. At the 0.05 level of significance, perform a hypothesis test to
see if the true mean weight is less than 4 ounces.
The correct null and alternative hypotheses are
A. H0 : µ = 4; HA : µ > 4
B. H0 : µ = 4; HA : µ < 4
C. H0 : µ > 4; HA : µ = 4
D. H0 : µ < 4; HA : µ = 4
E. H0 : µ = 4; HA : µ ≠ 4
IIIA-1
Copyright © 2015 Pearson Education, Inc.
,IIIA-2 Part III: Inference for Decision Making
Chapter 11: Perform hypothesis tests for means.
3. The weights of soy patties sold by Veggie Burgers Delight are normally distributed. A
random sample of 15 patties yields a mean weight of 3.8 ounces with a sample standard
deviation of 0.5 ounces. At the .05 level of significance, perform a hypothesis test to see
if the true mean weight is less than 4 ounces.
The correct calculated value of the test statistic is
A. -0.4
B. 0.4
C. -1.55
D. 1.55
E. 2.79
Chapter 13: Investigate and interpret P‐values in the context of t‐tests.
4. A sample of 30 year fixed mortgage rates at 12 randomly chosen credit unions yields a
mean rate of 6.65 % and a sample standard deviation of 0.38%. A sample of 30 year
fixed mortgage rates at 16 randomly selected banks yields a mean rate of 7.05% and a
sample standard deviation of 0.22%. Are the mean rates different between credit unions
and banks? Relevant output is shown below. At the 0.05 level of significance, the
correct conclusion is
Two-Sample T-Test and CI
Sample N Mean StDev SE Mean
1 12 6.650 0.390 0.11
2 16 7.050 0.220 0.055
Difference = mu (1) - mu (2)
Estimate for difference: -0.400
95% CI for difference: (-0.666, -0.134)
T-Test of difference = 0 (vs not =): T-Value = -3.19 P-Value = 0.006 DF = 16
A. Reject the null hypothesis.
B. Do not reject the null hypothesis.
C. Evidence suggests that there is a significant difference in mean mortgage rates
between credit unions and banks.
D. Both A and C.
E. Both B and C.
Chapter 12: Interpret and understand P‐values and alpha levels.
5. A P-value indicates
A. the probability that the null hypothesis is true.
B. the probability that the alternative hypothesis is true.
C. the probability of the observed statistic given that the null hypothesis is true.
D. the probability of the observed statistic given that the alternative hypothesis is
true.
E. None of the above.
Copyright © 2015 Pearson Education, Inc.
, Test A IIIA-3
Chapter 13: Investigate and interpret P‐values in the context of t‐tests.
6. A professor was interested in determining whether the prices of new textbooks in the
bookstore were higher than if purchased online. She selected 6 textbooks and priced each
at the bookstore and online.
Paired T for Bookstore - Online
N Mean StDev SE Mean
Bookstore 6 115.00 22.36 9.13
Online 6 105.83 13.20 5.39
Difference 6 9.17 13.20 5.39
95% lower bound for mean difference: -1.69
T-Test of mean difference = 0 (vs > 0): T-Value = 1.70 P-Value = 0.075
Based on her analysis, we can conclude at the 0.05 level of significance that
A. The prices are the same in the bookstore and online.
B. The prices are higher in the bookstore.
C. The prices are higher online.
D. The prices are different in the bookstore and online.
E. The analysis is not conclusive.
Chapter 12: Identify and understand Type I errors, Type II errors, and the power of a test.
7. Absorption rates into the body are important considerations when manufacturing a
generic version of a brand-name drug. A pharmacist read that the absorption rate into
the body of a new generic drug (G) is the same as its brand-name counterpart (B). She
has a researcher friend of hers run a small experiment to test H 0 : μG − μ B = 0 against the
alternative H A : μG − μ B ≠ 0 . Which of the following would be a Type I error?
A. Deciding that the absorption rates are the same, when in fact they are.
B. Deciding that the absorption rates are different, when in fact they are.
C. Deciding that the absorption rates are the same, when in fact they are not.
D. Deciding that the absorption rates are different, when in fact they are not.
E. The researcher cannot make a Type I error, since he has run an experiment.
Chapter 11: Create and interpret confidence intervals for the mean.
8. We have created a 95% confidence interval for µ with the result (10, 15). What
conclusion will we make if we test H 0 : µ = 16 versus HA : µ ≠ 16 at α = 0.05?
A. Reject the null hypothesis
B. Accept the null hypothesis
C. Fail to reject the null hypothesis.
D. Reject the alternative hypothesis.
E. No decision can be made from the information given.
Copyright © 2015 Pearson Education, Inc.
, IIIA-4 Part III: Inference for Decision Making
Chapter 10: Understand errors in hypothesis tests.
9. Suppose that a manufacturer is testing one of its machines to make sure that the
machine is producing more than 97% good parts ( H 0 : p = 0.97 and H A : p > 0.97 ) .
The test results in a P-value of 0.102. In reality, the machine is producing 99% good
parts. What probably happens as a result of our testing?
A. We correctly fail to reject H 0 .
B. We correctly reject H 0 .
C. We reject H 0 , making a Type I error.
D. We fail to reject H 0 , making a Type I error.
E. We fail to reject H 0 , making a Type II error.
Chapter 11: Perform hypothesis tests for means.
10. The weights of soy patties sold by Veggie Burgers Delight are normally distributed.
A random sample of 15 patties yields a mean weight of 3.8 ounces with a sample
standard deviation of 0.5 ounces. At the 0.05 level of significance, perform a hypothesis
test to see if the true mean weight is less than 4 ounces.
The correct conclusion at the 0.05 level of significance is
A. Do not reject the null hypothesis.
B. Reject the null hypothesis.
C. Evidence suggests that the mean weight is less than 4 ounces.
D. Both A and C.
E. Both B and C.
Chapter 13: Determine whether two samples are independent or paired.
11. A sample of 30 year fixed mortgage rates at 12 randomly chosen credit unions yields
a mean rate of 6.65 % and a sample standard deviation of 0.38%. A sample of 30 year
fixed mortgage rates at 16 randomly selected banks yields a mean rate of 7.05% and a
sample standard deviation of 0.22%. Are the mean rates different between credit unions
and banks? Relevant output is shown below. Which of the following is true?
Sample N Mean StDev SE Mean
1 12 6.650 0.390 0.11
2 16 7.050 0.220 0.055
Difference = mu (1) - mu (2)
Estimate for difference: -0.400
95% CI for difference: (-0.666, -0.134)
T-Test of difference = 0 (vs not =): T-Value = -3.19 P-Value = 0.006 DF = 16
A. This is a paired design.
B. This is a test of two means from independent samples.
C. This is a one tailed test.
D. Both A and C.
E. Both B and C.
Copyright © 2015 Pearson Education, Inc.
