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(4): Solution FINAL WORD by Brian Smith)

Both the formula and the solution are ok

I DID NOT NOTICE THAT YOU DEDUCTED THE 3 REDUNDANT CHOICES

errare humanum est

ady