Estimates of the prevalence of Alzheimer's disease have recently been provided by Pfeffer et al. [8]. The estimates are given in Table $3.5 .$ Suppose an unrelated 77 -year-old man, 76 -year-old woman, and 82-year-old woman are selected from a community.Suppose we know two of the three people have Alzheimer's disease. What is the conditional probability that they are both women?