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

Solution by Brian Smith)

B.S.

I have jusr re-read the question.

Your solution is right - mine is not.

I assumed exclusivity which was not requested.

I saluTe the author and upgrade my vote.

ady