To demonstrate set union and intersection to her class, Mrs. Putnam asked for three students to each write down a set of numbers.
After they had done so, she looked at their sets and told the class, "the union of these three sets is the first ten counting numbers, but their intersection is empty!"
How many triples (A, B, C) of sets are there such that
A U B U C = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
and
A ∩ B ∩ C = {} ?
(In reply to
re: my solution by Charlie)
Yes, sir I DO
However you are free to make other assumptions as long as you specify what is counted and what is not.
It does not look logical to dissallow two empty sets while ignoring one empty set...
ady
re(2): my solution
