- #1
Panphobia
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Homework Statement
Set A has twice the number of elements as Set B, 1/3 of the elements of Set A are the same as in Set B, the union of A and B is 42, what is the intersection?
The Attempt at a Solution
This was one of my exam questions, and I just want to see what the correct answer was. What I tried to do was
use the inclusion exclusion principle so
|AUB| = |A| + |B| - (1/3)*|A|
42 = |A| + 1/2|A| - (1/3)|A|
42 = (1/6)|A| + (3/6)*|A| - (2/6)*|A|
42 = (1/3)|A|
And 42 is the intersection, but that makes absolutely no sense, can anyone show me the correct way to get the answer?