Assume we have
n number of sets with varying number of elements, some of which appear in more than one set. Each element can have zero or more attributes.
If we are told that an element appears in all the sets, what is the probability that it has a specific attribute
As a concrete example, let's say we have two decks of standard playing cards, one missing the diamonds and one missing the clubs as well as spades. Now if a card that appears in both decks is picked, what is the probability that it's a heart?