1. A professor has been teaching statistics for many years. His records show that the overall mean for final exam scores is 85 with a standard deviation of 10. He believes that this year's class is superb to the previous classes. The mean for the 40 students is 90.
- What is the null hypothesis?
- What is the research hypothesis?
- Is this a one or two tailed hypothesis?
- Which test should you use? Why?
- Calculate the appropriate statistical test.
- What is the critical value for α = .05?
- What do you conclude?
2. A researcher gives a group of participants (n = 15) a memory technique to use. He finds that they remember on average 20 words (sample standard deviation = 3) while the average number of words remembered in the population is 15.
- What is the null hypothesis?
- What is the research hypothesis?
- Is this a one or two tailed hypothesis?
- Which test should you use? Why?
- Calculate the appropriate statistical test.
- What is the critical value for α = .05?
- What do you conclude?
3. What is the difference between a z-test and a t-test (i.e., when would you use each one)?