I'm working on the following problem taken from Casella and Berger's book on Statistical Inference:
I understand their view and could answer the whole problem as the suggested solution, but I rather disagree with the view exposed in item a). I understand that we should visualize the problem of having 5 sets of twins in a class of 60 people as having 10 (not 5) successes with the probability of 1/90 for each of them.
This is motivated by the statement that says that the probability of a twin birth is around 1/90. So, if a person is chosen randomly in the population, its chance of being a twin is 1/90. But if, for a given set of twin brothers, one of them goes to one school and the other one goes to another school these would not count as a "success" for our exercise, although they happen to be twins!!!
Can anyone explain me how this works? Thanks so much in advance!!!