1. Slide 10- 1 Copyright © 2010 Pearson Education, Inc. Active Learning Lecture Slides For use with Classroom Response Systems Business Statistics First Edition by Sharpe, De Veaux, Velleman Chapter 12: Confidence Intervals and Hypothesis Tests for Means

2. Slide 12- 2 Copyright © 2010 Pearson Education, Inc. Which of the following is not an assumption or condition that needs to be checked to construct a confidence interval for the mean using the Student’s t distribution? A. Randomization B. 10% Condition C. Success/Failure Condition D. Nearly Normal Condition

3. Slide 12- 3 Copyright © 2010 Pearson Education, Inc. Which of the following is not an assumption or condition that needs to be checked to construct a confidence interval for the mean using the Student’s t distribution? A. Randomization B. 10% Condition C. Success/Failure Condition D. Nearly Normal Condition

4. Slide 12- 4 Copyright © 2010 Pearson Education, Inc. Which statement correctly compares t-distributions to the normal distribution? I. t distributions and the Normal are symmetric. II. t distributions have less spread than the Normal distribution. III. t distributions and the Normal are bell shaped. A. I only B. II only C. I and II only D. I and III only

5. Slide 12- 5 Copyright © 2010 Pearson Education, Inc. Which statement correctly compares t-distributions to the normal distribution? I. t distributions and the Normal are symmetric. II. t distributions have less spread than the Normal distribution. III. t distributions and the Normal are bell shaped. A. I only B. II only C. I and II only D. I and III only

6. Slide 12- 6 Copyright © 2010 Pearson Education, Inc. Which of the following is true about Student’s t-models? A. They are unimodal and symmetric. B. They have fatter tails than the Normal model. C. As the degrees of freedom increase, the t- models look more and more like the Normal Model D. All of the above.

7. Slide 12- 7 Copyright © 2010 Pearson Education, Inc. Which of the following is true about Student’s t-models? A. They are unimodal and symmetric. B. They have fatter tails than the Normal model. C. As the degrees of freedom increase, the t- models look more and more like the Normal Model D. All of the above.

8. Slide 12- 8 Copyright © 2010 Pearson Education, Inc. A researcher found that a 98% confidence interval for the mean hours per week spent studying by college students was (13, 17). Which is true? A. There is a 98% chance that the mean hours per week spent studying by college students is between 13 and 17 hours. B. We are 98% sure that the mean hours per week spent studying by college students is between 13 and 17 hours. C. Students average between 13 and 17 hours per week studying for 98% of the weeks. D. 98% of all students spend between 13 and 17 hours studying per week.

9. Slide 12- 9 Copyright © 2010 Pearson Education, Inc. A researcher found that a 98% confidence interval for the mean hours per week spent studying by college students was (13, 17). Which is true? A. There is a 98% chance that the mean hours per week spent studying by college students is between 13 and 17 hours. B. We are 98% sure that the mean hours per week spent studying by college students is between 13 and 17 hours. C. Students average between 13 and 17 hours per week studying for 98% of the weeks. D. 98% of all students spend between 13 and 17 hours studying per week.

10. Slide 12- 10 Copyright © 2010 Pearson Education, Inc. The owner of small specialty store was interested in the amount customers spent on designs from a local artist. From a random sample of 20 customers, she found a mean of $375 with a standard deviation of $56. To construct a 95% confidence interval for the true mean amount spent, she would use a t value of A. 1.729 B. 2.093 C. 1.96 D. 3.078

11. Slide 12- 11 Copyright © 2010 Pearson Education, Inc. The owner of small specialty store was interested in the amount customers spent on designs from a local artist. From a random sample of 20 customers, she found a mean of $375 with a standard deviation of $56. To construct a 95% confidence interval for the true mean amount spent, she would use a t value of A. 1.729 B. 2.093 C. 1.96 D. 3.078

12. Slide 12- 12 Copyright © 2010 Pearson Education, Inc. A professor was curious about her students’ grade point averages (GPAs). She took a random sample of 15 students and found a mean GPA of 3.01 with a standard deviation of 0.534. Which of the following formulas gives a 99% confidence interval for the mean GPA of the professor’s students? A. B. C. D.

13. Slide 12- 13 Copyright © 2010 Pearson Education, Inc. A professor was curious about her students’ grade point averages (GPAs). She took a random sample of 15 students and found a mean GPA of 3.01 with a standard deviation of 0.534. Which of the following formulas gives a 99% confidence interval for the mean GPA of the professor’s students? A. B. C. D.

14. Slide 12- 14 Copyright © 2010 Pearson Education, Inc. A coffee house owner knows that customers pour different amounts of coffee into their cups. She samples cups from 10 costumers she believes to be representative of the customers and weighs the cups, finding a mean of 12.5 ounces and standard deviation of 0.5 ounces. Which of the following formulas gives a 95% confidence interval for the mean weight of all cups of coffee? A. B. C. D.

15. Slide 12- 15 Copyright © 2010 Pearson Education, Inc. A coffee house owner knows that customers pour different amounts of coffee into their cups. She samples cups from 10 costumers she believes to be representative of the customers and weighs the cups, finding a mean of 12.5 ounces and standard deviation of 0.5 ounces. Which of the following formulas gives a 95% confidence interval for the mean weight of all cups of coffee? A. B. C. D.

16. Slide 11- 16 Copyright © 2010 Pearson Education, Inc. After instituting some improvements, a bank wished to test whether service times at the drive through window improved. The average service time had been 110 seconds. A sample of 25 customers resulted in a mean of 100 seconds with a standard deviation of 40 seconds. Which hypotheses should they test? A. H 0 : µ 110 B. H 0 : µ = 110 H A : µ > 110 C. H 0 : µ > 100 H A : µ = 100 D. H 0 : µ = 110 H A : µ < 110

17. Slide 11- 17 Copyright © 2010 Pearson Education, Inc. After instituting some improvements, a bank wished to test whether service times at the drive through window improved. The average service time had been 110 seconds. A sample of 25 customers resulted in a mean of 100 seconds with a standard deviation of 40 seconds. Which hypotheses should they test? A. H 0 : µ 110 B. H 0 : µ = 110 H A : µ > 110 C. H 0 : µ > 100 H A : µ = 100 D. H 0 : µ = 110 H A : µ < 110

18. Slide 11- 18 Copyright © 2010 Pearson Education, Inc. After instituting some improvements, a bank wished to test whether service times at the drive through window improved. The average service time had been 110 seconds. A sample of 25 customers resulted in a mean of 100 seconds with a standard deviation of 40 seconds. What is the value of the calculated t statistic? A. -1.25 B. 0.25 C. 2.75 D. -2.35

19. Slide 11- 19 Copyright © 2010 Pearson Education, Inc. After instituting some improvements, a bank wished to test whether service times at the drive through window improved. The average service time had been 110 seconds. A sample of 25 customers resulted in a mean of 100 seconds with a standard deviation of 40 seconds. What is the value of the calculated t statistic? A. -1.25 B. 0.25 C. 2.75 D. -2.35

20. Slide 11- 20 Copyright © 2010 Pearson Education, Inc. After instituting some improvements, a bank wished to test whether service times at the drive through window improved. The average service time had been 110 seconds. A sample of 25 customers resulted in a mean of 100 seconds with a standard deviation of 40 seconds. What can we conclude? A. The mean service time increased. B. The mean service time did not decrease. C. The test is inconclusive. D. The mean service time decreased.

21. Slide 11- 21 Copyright © 2010 Pearson Education, Inc. After instituting some improvements, a bank wished to test whether service times at the drive through window improved. The average service time had been 110 seconds. A sample of 25 customers resulted in a mean of 100 seconds with a standard deviation of 40 seconds. What can we conclude? A. The mean service time increased. B. The mean service time did not decrease. C. The test is inconclusive. D. The mean service time decreased.