Logical Venn Diagrams Level 3: Set Overlaps and Class Relationships
This Level 3 set tests two-set and three-set counting, the least and greatest possible overlaps, percentage surveys and matching groups of classes to the right circle diagram. It is free practice on Aptitude360 for the Logical Reasoning syllabus, and every question has a detailed written solution.
Topics covered in this Level 3 Venn diagram set
- Two-set problems with a neither group, including only-one and exactly-one counts
- Three-set problems using pairwise and triple overlaps to find exactly-two and none counts
- Least and greatest possible overlap of two or three sets, and the gap between them
- Percentage surveys where a known overlap gives the total population
- Class relationships among numbers, elements, gases and everyday categories
- Matching nested, overlapping or disjoint circle arrangements to the correct classes
Key set formulas for Venn diagram counting
- Union of two sets: \( n(A\cup B)=n(A)+n(B)-n(A\cap B) \)
- Only A, out of three sets: \( n(A)-n(A\cap B)-n(A\cap C)+n(A\cap B\cap C) \)
- In neither set, where \( n(U) \) is the total: \( n(U)-n(A\cup B) \)
- Least overlap of two sets: \( \max\{0,\ n(A)+n(B)-n(U)\} \)
- Greatest overlap of two sets: \( \min\{n(A),\ n(B)\} \)
- Least triple overlap: \( \max\{0,\ n(A)+n(B)+n(C)-2n(U)\} \)
Class relationship ideas to revise
- One class lying wholly inside another, such as an element inside its group
- Two classes that partly overlap inside a larger class
- Classes with nothing in common, drawn as separate circles
- How the stated universe, such as positive integers only, changes the answer
Revision tips for harder Venn diagram questions
- Fill the region common to all sets first, then work outward to the single-set regions
- Convert every percentage to one base before using a given count to find the total
- For extreme overlaps, test the smaller set fully inside the larger and the sets spread as far apart as the total allows
Who this Level 3 set suits
Logical reasoning learners who are comfortable with basic Venn diagrams and now want tougher two-set and three-set practice.