Logical Venn Diagrams
Choosing the diagram that fits a set of related terms by checking every pair of classes, and reading a region-count diagram to answer 'how many are in X but not Y'.
What you will be able to do
- Classify each pair of terms as separate, one-inside-the-other, or overlapping.
- Pick the single diagram that satisfies every pairwise relation at once.
- Read a region-count diagram to find 'only X', 'X and Y', and 'at least one'.
- Avoid the trap of forcing an overlap that real-world meaning rules out.
What is inside this lesson
- 1Two forms of the question
- 2Three ways two classes can relate
- 3Choosing the diagram
- 4Reading a region-count diagram
- 5Worked examples
- 6Common mistakes
- 7Quick revision
- 8Practice
Get Pro for full access. This is section 1 of 8; the rest of the lesson opens with Pro at onelystop.in/upgrade.
Two forms of the question
Choose the diagram. You are given three or four class names, such as Men, Fathers, Doctors, and must pick the circle picture that shows how they sit together.
Read the counts. You are given a filled-in diagram with a number in each region and asked for something like 'how many play cricket but not football'.
The first form tests whether you can classify every pair of classes correctly. The second is careful addition over the right regions.
Reading the 8 sections above is free. A free account opens the first 2 topics of every subject in full, along with flashcards and private notes.