28. In a study of the role of dietary fats in the etiology of ischemic heart disease the subjects were 60 males between 40 and 60 years of age who had recently had a myocardial infarction and 50 apparently healthy males from the same age group and social class.

One variable of interest in the study was the proportion of linoleic acid (L.A.) in the subjects' plasma triglyceride fatty acids. The data on this variable were as follows:

Subjects with Myocardial Infarction Subject L.A. Subject L.A. Subject L.A. Subject L.A.

1 18.0 2 17.6 3 9.6 4 5.5 5 16.8 6 12.9 7 14.0 8 8.0 9 8.9 10 15.0 11 9.3 12 5.8 13 8.3 14 4.8 15 6.9 16 18.3 17 24.0 18 16.8 19 12.1 20 12.9 21 16.9 22 15.1 23 6.1 24 16.6 25 8.7 26 15.6 27 12.3 28 14.9 29 16.9 30 5.7 31 14.3 32 14.1 33 14.1 34 15.1 35 10.6 36 13.6 37 16.4 38 10.7 39 18.1 40 14.3 41 6.9 42 6.5 43 17.7 44 13.4 45 15.6 46 10.9 47 13.0 48 10.6 49 7.9 50 2.8 51 15.2 52 22.3 53 9.7 54 15.2 55 10.1 56 11.5 57 15.4 58 17.8 59 12.6 60 7.2 Healthy Subjects Subject L.A. Subject L.A. Subject L.A. Subject L.A.

1 17.1 2 22.9 3 10.4 4 30.9 5 32.7 6 9.1 7 20.1 8 19.2 9 18.9 10 20.3 11 35.6 12 17.2 13 5.8 14 15.2 15 22.2 16 21.2 17 19.3 18 25.6 19 42.4 20 5.9 21 29.6 22 18.2 23 21.7 24 29.7 25 12.4 26 15.4 27 21.7 28 19.3 29 16.4 30 23.1 31 19.0 32 12.9 33 18.5 34 27.6 35 25.0 36 20.0 37 51.7 38 20.5 39 25.9 40 24.6 41 22.4 42 27.1 43 11.1 44 32.7 45 13.2 46 22.1 47 13.5 48 5.3 49 29.0 50 20.2 Construct the 95 percent confidence interval for the difference between population means. What do these data suggest about the levels of linoleic acid in the two sampled populations?