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Trouble with set theory!

Problem Solving — algebra and arithmetic
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by Stuart@KaplanGMAT » Tue Feb 09, 2010 11:35 pm
The two formulae should be enough to answer any 3 set question, yes; the other formulae in the link you shared are just variations of it.

I suppose you could memorize a different variation for every possible question (i.e. isolate a different variable), but I really wouldn't advise it - it's unlikely you'll see more than 1 overlapping set question on test day and there are far more important topics on which to spend your time and brainpower.
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by shashank.ism » Wed Feb 10, 2010 12:03 am
papgust wrote:Stuart,

Thanks for your prompt response. I've seen some problems of that type. I tried to search for those type of questions but couldn't find any. However, i came across a post here.

https://www.beatthegmat.com/formulas-for ... 16479.html

This post tells that for "exactly 2 of the sets" problems, intersection of all must be subtracted thrice.

I'm actually overwhelmed by seeing so many forumale in this link. I've a couple of questions for you.

1. Do we really need to know these for GMAT?
2. Can we actually answer any type of questions (as posted in the link) with the 2 formulae you shared with us in this thread?
Papgust It would be of great help to you if you draw venn diagrams to understand the concepts. As I have done when I was confused a bit on P(AnBnC). The link of the diagram is
https://www.postimage.org/image.php?v=PqWkNVr
It was of great help and cleared all concept. I think we discussed one question of such type in post "sets" https://www.beatthegmat.com/sets-t52148.html#223204
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