1. Assume that a population of thousands of people whose responses were used to develop an anxiety test had scores that were normally distributed with M = 30 and s = 10. What proportion of people in this population would have anxiety scores within each of the following ranges of scores?
• Below 20.
• Above 30.
• Between 10 and 50.
2. What is SEM? What does the value of SEM tell you about the typical magnitude of sampling error?
• As s increases, how does the size of SEM change (assuming that N stays the same)?
• As N increases, how does the size of SEM change (assuming that s stays the same)?
3. Under what circumstances should a t distribution be used rather than the normal distribution to look up areas or probabilities associated with distances from the mean?