Estimates of the prevalence of Alzheimer's disease have recently been provided by Pfeffer et al. . The estimates are given in Table 3.5. Table 3.5 Prevalence of Alzheimer's Disease (Cases per 100 Population) Age group Males Females 65-69 1.6 0.0 70-74 0.0 2.2 75-79 4.9 2.3 80-84 8.6 7.8 85+ 35.0 27.9 Suppose an unrelated 77-year-old man, 76-year-old woman, and 82-year-old woman are selected from a community