I was looking at the Set Theory Made Easy post and I couldn't see how to apply it to this:
Sets A B and C have some elements in common. If 16 elements are in both A and B, 17 in both A and C, and 18 in B and C, how many elements do all three of the sets have in common?
I: Of the 16 elements that are in both A and B, 9 are also in C
II: A has 25 elements, B has 30 elements, and C has 35 elements.
What's the easy way to do this?
My initial answer was A. Did S2 first, which is obvs insuff.
I'm not sure if this is right, but since AB have 16 in common and C has 9 in common with these, then shouldnt all 3 have 9 in common???