My text is lacking a clear example on this one.
Given the following information
Suppose an unrelated 77 year old man, a 76 year old woman and an 82 year old woman are selected from a community.
Prevalence of Alzheimer’s disease (cases per 100)
Age Group Males Females
65-69 1.6 0
70-74 0 2.2
75-79 4.9 2.3
80-84 8.6 7.8
85+ 35 27.9
1) What is the probability that all three have Alzheimer’s disease?
Let A = 77 year old man has Alzheimer’s
Let B = 76 year old woman has Alzheimer’s
Let C = 82 year old woman has Alzheimer’s
I say the answer is P(A) x P(B) x P(C) = 4.9/100 x 2.3/100 x 7.8/100
2) What is the probability that at least one of the women have Alzheimer’s disease?
Do I need to apply Baye's thm here? Or is it some binomial thing where I find p = 2.3/100 x 7.8/100
3) What is the probability that at least one of the three have Alzheimer’s disease?
If my method for Q2 is correct I would try something similar here.
Thanks for your interest...