BansalT wrote:
Hi while solving overlapping kind of ques. I get confused whether to start with a Venn diagram or a tabular format or simply using formula. Hence it takes a lot of time like around 3 min. Can someone please guide me on the better approach to quickly decide how to solve the ques.
First, you should determine if it is a TWO GROUP or a THREE GROUP overlapping set.
If it's two group, I think the answer is unambiguously to *build the overlapping set Matrix.*
I find it a much more useful construct than either Venn Diagrams or the formula. It has a box for every possible number you could get in a two group overlapping set question: Both, Neither, A only, B only, All A, All B, All NOT A, All NOT B, Total.
No formula or venn diagram has convenient places for these, every time. And you don't have to memorize a formula at all.
For 3x3, it gets a little trickier. There are a few different formulas that you have to know, depending on how the problem gives the information, and that gets a little annoying. I think a Venn Diagram is best, and to practice building an equation while keeping track of which sections you've counted in the Venn Diagram, and how many times they're counted. You want to get to an equation where every part is counted *only once*, so you need to add/subtract the 'sections' of the venn diagram until that happens.
This video covers overlapping sets, both 2 and 3 group. It might be useful for you to watch.