Reasoning - Logical Venn Diagrams

It is a process of showing complex relationship between 2-3 categories diagrammatically through various geometric strictures. Intersection between two geometric structures indicate that they have something in common and total isolation indicates just opposite of that. Though the theory seems to be complex from above but a basic understanding of various types of sample cases will help in solving the coming questions more easily.

Take a look upon various possible cases of venn diagram and know when it is applicable. Among three columns, first one shows the type of venn diagram, second one is for description and third one sites an example to give a clear picture of the description.

Venn diagram	Applicable cases	Example
	There will be a series of sub cases one under another.	Colour>Green>light green. Light green colour is a sub part of green colour and both of them belongs to colour group.
	One main category, under it two sub categories and both bear some similarities among them.	Liquids>Petrol, diesel. Here both are flammables in nature, thus bear similarity.
	One category may have one sub category. They both partially satisfy some conditions (not always).	Vegetable>Capsicum>Red. Some capsicums are red and so as some other vegetables.
	Among three different sections, two may have some common properties those do not match with third one.	Actor>Headmaster>Queen. From the above, actor and headmaster are showing masculinity, thus bearing some common properties which is just opposite to Queen.
	Three sections having no common feature.	Tree>Angry>Coffee. There is no logic of finding any common aspect among above three terms.
	There is a chance of finding a common place that satisfies all the properties of three individual sections.	Mother>Step mother>Sister-in law. A single woman can be all of the above said simultaneously.
	This is particular for those cases in which out of three sections, two are inter related as parent child relationship, whereas third one has no relation with them.	Tree>banana tree>Angry. We all know banana tree is coming under tree category but emotion” Angry” has nothing to do with these 2 words.

Another type of question that often comes under this chapter is intersection of various geometric structures. Each geometric structures will be having some elements of their own and each structure will bear some characteristics or class. Intersection of two or more structures will give an amalgamation that will change the property of each previous element by something new. We have to identify that and need to answer accordingly from the given options.

Five people are numbered and have some characteristics. Study the diagram to answer correctly.

1 - Which number person is smart and cute?

A - 1

B - 2

C - 3

D - 4

Answer − Option B

Explanation − Number 2 lies in the common area of square and circle thus bears the characteristics of both structures.

2 - Which number person is smart but neither polite nor cute?

A - 1

B - 2

C - 3

D - 4

Answer − Option D

Explanation − Number 4 lies in the circle area thus bear only the characteristics of being smart.

3 - Which number person is smart, polite and cute?

A - 1

B - 2

C - 3

D - None of the above

Answer − Option D

Explanation − No such number is there that lies in the intersection area of all three geometrical structures.