I keep seeing that one in five of us will die from cancer.
So in a family of five, each of us has a 20% chance of dying from it individually, but what is the chance of the family as a whole having someone dying from it? Clearly it is not 100% as another family of five might have two die in it and you have none.
I am ignoring the heredity factor in some types of cancer, just assume the cases happen at random.
I would be grateful for any help as this sort of problem has been puzzling me for a while!