A researcher believe that college students spend a different amount of time talking on the phone than they do instant messaging. She takes a random sample of 12 college students and records the number of hours per week each student spends on each activity and plans to test at the 5% level.

1. Based on the description of how the data were gathered, which test design is appropriate?

2. What is the parameter of interest? Describe in words in the context of the problem

3. For the test to be valid, what TWO assumptions must be made?

4. For the sample of 12 students, the mean number of hours of phone use per week was 27.9 and the standard deviation was 1.6. The mean number of hours of instant messaging per week was 25.3 and the standard deviation was 3.7. The sample mean difference was 2.7 and the standard deviation of the differences was 3.3. Calculate the test statistic. Show your work.

5. Is this a one-sided or two-sided test?

6. What is the value of the degrees of freedom for this test?

7. Give bounds for the p-value for this test.

8. Based on the p-value you calculated, what is your statistical decision?

9. Provide a conclusion in the context of the problem.

10. Give the null and alternative hypotheses for this test.