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(2): Solution FINAL WORD by Charlie)

no ,they were not...
try it with 4 numbers only 1 2 3 4 with the same restrictions and you will see that his formula FAILS...

ady

Posted by Ady TZIDON on 2004-02-10 14:50:41