SSC CGL Reasoning · Venn Diagrams
Logical Venn Diagrams
Three classes are named and you pick the diagram of circles that shows how they relate: one inside another, overlapping, or apart.
Why this matters
Thirty questions in the bank, 29 of them from the 2023 shifts, with 26 EASY and 4 MODERATE. Each is decided by three yes-or-no questions about pairs of classes, so it should take under 20 seconds once the habit is set.
Concept 1 of 2: Inside or apart
Definition
- Inside: every A is a B (every alligator is a reptile), so circle A sits inside circle B.
- Nested: if also every B is a C, the three circles sit one inside another.
- Apart: no A is a B (no snake is a crocodile), so the two circles do not touch.
- Two kinds of one thing: two classes that are both kinds of a third but never each other become two separate circles inside one large circle.
- Unrelated: a class with nothing in common with the others (a city beside two currencies) is a circle on its own, outside the rest.
- Fast route: settle the pair you are surest of first, strike the options that draw it wrongly, then check the next pair.
Worked example
Practice this conceptself-check · 4 quick reps
The same idea in a real exam question:
Example 1 · Venn Diagrams · Logical Venn Diagrams
Putting the larger class inside the smaller one
Overlapping two kinds that never meet
Concept 2 of 2: Overlapping classes
Definition
- Overlap: some A are B, some A are not B, and some B are not A. The circles cross.
- Three overlapping circles: each pair can share members and some members are in all three (teachers, singers and dancers).
- One circle crossing two separate ones: students overlap boys and overlap girls, but no one is both a boy and a girl.
- Inside and crossing: mothers sit inside women, and doctors cross both circles.
- Check every pair: for three classes there are three pairs, and each pair is inside, apart or overlapping.
- Fast route: a job or a hobby nearly always overlaps a group of people; a kind of thing nearly always sits inside the larger kind.
Worked example
Practice this conceptself-check · 4 quick reps
The same idea in a real exam question:
Example 2 · Venn Diagrams · Logical Venn Diagrams
Drawing an overlap where one class is inside the other
Forgetting the members outside
Summary — formulas & gotchas at a glance
A revision cheat-sheet for the formulas and gotchas above. Click any concept name to jump back to its full explanation.
Watch out for (4)
- Putting the larger class inside the smaller one→ Inside or apart
- Overlapping two kinds that never meet→ Inside or apart
- Drawing an overlap where one class is inside the other→ Overlapping classes
- Forgetting the members outside→ Overlapping classes
Test yourself on Venn Diagrams
15 past SSC CGL questions from this chapter, timed at 9 minutes and marked the way the exam marks it. You see your score and every answer the moment you finish. Free to start.