Would you expect a positive, negative, or nearly zero correlation for each of the following? Give reasons for your answers.
(a) The time a student spends playing computer games each week and the time they spend talking with friends in a group.
(b) The number of finals taken by undergraduates and their number of hours of sleep during finals week.
(c) A person's height and the number of movies he or she watched last month.
(d) The temperature at a baseball game and beer sales.