Read the following scenarios. For each scenario you need to decide which of the following four methods is appropriate.

A. One sample t test (6 of them)

B. Paired samples t test (5 of them)

C. Independent samples t test (5 of them)

D. One-way analysis of variance (ANOVA) (4 of them)

1. The U.S. Department of Transportation provides estimated number of miles that residents of large metropolitan areas travel per day in a car. In a random sample of 50 City A residents the mean was 22 miles with a standard deviation of 4 miles, and in a random sample of 50 City B residents the mean was 28 miles with a standard deviation of 8 miles. You want to know if the mean difference in number of miles travelled per day between City A and City B is different from zero in the population.

2. An educator has collected a sample of students who took the SAT twice, the first time before any SAT-specific tutoring, and the second time after receiving such tutoring. She wants to know if the mean SAT score differs significantly before and after receiving tutoring.

3. An IRS analyst is interested in testing the hypothesis that for a sample of 8,109 individuals the average federal income tax return in the most recent tax year is $1,035.

4. All employees in a firm have recently received professional development training that is designed to improve their productivity. A manager wants to know whether or not the training has been effective by comparing employee productivity data before and after the training.

5. A reputed financial magazine has reported that the average salary of accountants across the U.S. is $85,000. You are interested in testing this claim based on the current salary of 42 accountants in your accounting firm.

6. All employees in a firm have recently received professional development training that is designed to improve their productivity. A manager wants to know whether or not the post-training productivity differs significantly between female and male employees.

7. A shareholders' group suspects that the mean tenure of corporate chief executive officers (CEO) is significantly greater than the 5 years that CEO supporters claim. The group has hired a statistician who is using information on tenure of the last retired CEO in a sample of 30 corporations to test this claim.

8. All employees in a firm have recently received professional development training that is designed to improve their productivity. A manager wants to know whether or not the post-training productivity differs significantly across low-, medium-, and high-education employees.

9. A computer manufacturer has designed twenty-three prototype microcomputer central processing unit chips, and is using a sample of 506 computers (22 computers carrying each prototype) to evaluate whether the mean processing time differs significantly across the twenty-three prototypes.

10. In a blind taste experiment a group of potential customers were asked to rate the taste of two different coffee brands on a scale of 0 to 10. The experimenter wants to know whether or not on average the ratings differ for the brands.

11. A bank manager wants to know whether or not the average waiting time for bank customers is significantly different between two local branches of that bank.

12. A national auto dealers association claims that the mean price of a used car is $9,987. A used car dealership manager located in the City of Baltimore wants to test this claim using a sample of 45 cars currently parked at the dealership.

13. A computer manufacturer has discovered a method to improve performance of existing CPU chips by coating those chips with a fine layer of a special patented chemical. The manufacturer wants to test the effectiveness of this method in two groups of similar computers. The CPU chips in only one group have received a coating of the special chemical.

14. A computer manufacturer has discovered a method to improve performance of existing CPU chips by coating those chips with a fine layer of a special patented chemical. The manufacturer wants to test the effectiveness of this method in a sample of 54 computers by observing CPU performance before and after applying the coating.

15. A local landscaping business owner wants to test the hypothesis that the mean tree planting time differs significantly from 2 hours for her employees.

16. An educator wants to test the hypothesis that average SAT score in the population is the same in Belgium, Denmark, and Netherlands.

17. Using random state-level household samples, a social scientist wants to know whether or not the mean household size is the same across 50 states in the U.S.

18. It has been claimed that average nursing salaries in Milwaukee, Wisconsin are lower than those in Pittsburgh, Pennsylvania. A medical professional wants to test this claim using a sample of salaries from the two cities.

19. A student government representative at a mid-sized East Coast university wants to test the mean difference in GPA at the beginning and end of the freshman year using a sample of 89 undergraduate students.

20. All employees in a firm have recently received professional development training that is designed to improve their productivity. The training provider claims that such training increases employee productivity by 10%. A firm manager has obtained estimates of change in productivity for 32 employees who received the training, and wants to test the training provider's claim.