Logical Venn — Relationship Between Groups

🎯 Learning Objective

Pick the correct circle diagram for a set of related words like Dog, Animal, Pet.

💡 Concept

• A Venn diagram shows how groups (classes) are related using circles
• ALL of one inside another → one circle sits fully inside the other (Dog inside Animal)
• SOME common → the two circles partly overlap (Dog and Pet)
• NOTHING common but same family → separate circles inside a bigger one (Table and Chair inside Furniture)
• Between every pair, ask just one question: all, some, or none?
• Classic trio Dog–Animal–Pet: every dog is an animal, every pet is an animal, and only some dogs are pets

✏️ Easy Example

Q. Choose the relationship: Dog, Animal, Pet.

1. Every dog is an animal → Dog circle sits fully inside Animal
2. Every pet is an animal → Pet circle also sits fully inside Animal
3. Only some dogs are pets → Dog and Pet overlap partly

Answer: One big Animal circle holding a Dog circle and a Pet circle that partly overlap each other

🇮🇳 Real-Life Example

Think of your mohalla: 'people who own a bike' and 'people who own a car' — some own both (the overlap), and both groups live inside the bigger circle 'residents of the colony'.

📝 Exam-Level Example

Q. Choose the relationship: Delhi, India, Asia.

1. Delhi is inside India, India is inside Asia
2. Each one is fully contained in the next bigger one

Answer: Three circles one inside another (Delhi inside India inside Asia) — called concentric

📝 Exam-Level Example

Q. Choose the relationship: Pen, Pencil, Stationery.

1. A pen is stationery, a pencil is stationery → both inside Stationery
2. A pen is never a pencil → no overlap between them

Answer: A big Stationery circle with two separate, non-touching circles (Pen and Pencil) inside it

📝 Exam-Level Example

Q. Choose the relationship: Students, Girls, Players.

1. Some students are girls, some students are players
2. Some girls are players too → all three share common parts

Answer: Three partly overlapping circles (each pair shares some members)

🪄 Memory Trick

Between each pair ask 'all / some / none'. ALL → circle inside circle; SOME → partial overlap; NONE but related → separate circles inside a bigger family circle.

⚠️ Common Mistakes

• ❌ Overlapping circles when one group is fully inside another (all dogs are animals → inside, not overlap)
• ❌ Drawing Table and Chair as overlapping — they are separate types of furniture, nothing common
• ❌ Assuming two words overlap just because they sound related — check with a real example

🏆 Exam Tips

• ✅ Test each option with one concrete example — 'is there a dog that is NOT an animal?' If no, Dog goes fully inside
• ✅ Words like 'always/every' signal a circle inside a circle; 'some' signals an overlap

📌 Summary

• Circles show group relationships: inside, overlap, or separate
• All → one inside another; Some → overlap; None (same family) → separate
• Dog–Animal–Pet: Dog and Pet inside Animal, Dog and Pet overlap
• Decide every pair with the all/some/none question