12.

Upper half Lower half 13.

Book 1 Book 2 Book 3 18 30 12 34 10 16 60 60 40 Do the data indicate that the distribution of preferences for students in the upper half of the class is significantly different from the distribution for students in the lower half? Test at the .05 level of significance.

Friedman and Rosenman (1974) have suggested that personality type is related to heart disease.

Specifically, type A people, who are competitive, driven, pressured, and impatient, are more prone to heart disease. On the other hand, type B individuals, who are less competitive and more relaxed, are less likely to have heart disease. Suppose that an investigator would like to examine the relationship between personality type and disease. For a random sample of individuals, personality type is assessed with a standardized test. These individuals are then examined and categorized as to whether they have a heart disorder.