Set Theory.. (Cphill, move your eyes over on this question plz)

Question

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In three sets Q, R and S, the following conditions are found.

In Q ∩ R there are 9 elements.

In Q ∩ S there are 4 elements.

In R ∩ S there are 11 elements.

If (Q ∩ R) ∪ (Q ∩ S) ∪ (R ∩ S) includes 18 elements, how many elements are in Q ∩ R ∩ S?

Thanks for viewing my problem.

(Cphill, move your eyes over on this question plz)

MathyGoo13 Apr 25, 2021

edited by MathyGoo13 Apr 25, 2021

CPhill · Answer 1 · 2021-04-25T11:53:21

Don't know how to solve this one, MG.......maybe someone else does....(sorry !!! )

catmg · Answer 2 · 2021-04-26T12:54:25

Hello :))

In Q and R there are 9.

In Q and S there are 4.

In R and S there are 11.

Combined, there are 18 elements, so there are 3 elements that are the same (9+4+11-18)/2.

I find it easier to visualize it through a venn diagram.

=^._.^=