Analogy and Classification — Revision Notes
Reasoning and Military Aptitude is the largest AFCAT section, and analogy and classification are its bread-and-butter openers - quick if you spot the relationship, costly (-1) if you guess. Both test the SAME skill: identify the rule linking items, then apply or break it.
Analogy: find the relationship, then match
An analogy "A is to B as C is to ?" works when the C:? pair shares B's exact relationship with A. Common relationships:
- Synonym/antonym (hot:cold), part-whole (wheel:car), worker-tool (writer:pen), cause-effect (fire:smoke), category (rose:flower), function (knife:cut).
- Number analogies: squares (2:4, 3:9), cubes, +/x patterns.
Classification (odd one out)
Four items follow one rule; one breaks it. Find the shared property (all primes, all fruits, all square numbers) and pick the exception. In "8, 27, 64, 100", the first three are perfect cubes (2^3, 3^3, 4^3) but 100 is not - so 100 is the odd one.
Exam Tricks & Tips
- 🎯 State the relationship in a short sentence ("A is the tool of B") before checking options.
- 🎯 If two options seem to fit, tighten the relationship - the exam wants the CLOSEST match.
- 🎯 For number analogies, test squares, cubes and simple +/x rules first.
- 🎯 In classification, the rule is usually a shared property; find it, then spot the one that fails it.
- 🎯 Watch the ORDER in analogies - A:B is directional, so keep C:? in the same direction.
- ❌ Common mistake: matching on surface similarity (same topic) instead of the exact logical relationship - rose:flower is category, not part-whole.
Quick recap
Name the exact relationship, respect its direction, and pick the closest match; for classification, find the common rule and eliminate the exception. These are fast, high-frequency reasoning marks.
Analogy and Classification — Flashcards
Cover the answer, recall, then check. 11 analogy-and-classification cards for AFCAT.
Q1. How does an analogy A:B :: C:? work?
A1. The C:? pair must share the exact same relationship that B has with A.
Q2. What relationship links "wheel : car"?
A2. Part to whole.
Q3. Odd one out: 8, 27, 64, 100 — which and why?
A3. 100 — the others are perfect cubes (2^3, 3^3, 4^3); 100 is not.
Q4. "Writer : pen" shows which relationship?
A4. Worker to tool.
Q5. First step before checking analogy options?
A5. State the relationship in a short sentence.
Q6. What number rules should you test first in analogies?
A6. Squares, cubes and simple + or x patterns.
Q7. "Fire : smoke" is which relationship?
A7. Cause to effect.
Q8. Why does order matter in analogies?
A8. A:B is directional, so C:? must follow the same direction.
Q9. In classification, what are you looking for?
A9. The common rule/property shared by all but one item.
Q10. "Rose : flower" — part-whole or category?
A10. Category (a rose is a type of flower).
Q11. Common analogy mistake?
A11. Matching on surface topic instead of the exact logical relationship.
Analogy and Classification
Analogy ("A is to B as C is to ?") and classification ("find the odd one out") are the opening act of AFCAT reasoning — quick, logical and highly scoring. Both test the same skill: spotting the relationship that binds a set of items. Nail the relationship and the answer is forced.
Core idea / what this tests: whether you can identify the precise logical relationship between a pair (analogy) or within a group (classification) and apply or break it consistently.
Deep explanation
Beginner — name the relationship
In an analogy, first state the link in words. "Doctor : Hospital" → "works in." Then apply the same link to the second pair: "Teacher : ?" → School. Common relationship types:
| Type | Example |
|---|---|
| Worker : Workplace | Pilot : Cockpit |
| Cause : Effect | Fire : Smoke |
| Tool : Function | Pen : Write |
| Part : Whole | Wheel : Car |
| Object : Material | Shirt : Cloth |
| Synonym / Antonym | Big : Large / Up : Down |
Intermediate — classification is analogy inverted
In "odd one out," four of five items share a property; one breaks it. Find the shared rule (all metals, all even numbers, all mammals) and the exception stands out. Test systematically: category, number property, spelling pattern. E.g. Apple, Mango, Carrot, Banana → Carrot is a vegetable; the rest are fruits.
Advanced — precision beats the "close" trap
Setters plant an option that fits a loose version of the relationship but not the exact one. Make the relationship as specific as possible. If "Cow : Calf" means "adult : its young," then "Dog : Puppy" fits but "Dog : Kennel" (a workplace-style link) does not. When two options seem to fit, tighten the rule until only one survives. For number analogies, check arithmetic links (square, cube, +/×, prime).
Worked example
Q. Hand : Glove :: Foot : ? (a) Sock (b) Shoe (c) Leg (d) Toe
State the link precisely: a glove is worn on the hand as an outer covering. The item worn on the foot as an outer covering is a shoe (a sock is an under-layer; leg and toe are body parts, not coverings). Answer: (b) Shoe. The tight relationship rejects the near-miss "sock."
AFCAT relevance
Analogy and classification appear reliably in AFCAT's reasoning section and are among the fastest questions to solve. Because they reward a clear rule rather than calculation, they let you build early momentum and save time for heavier reasoning types — while negative marking rewards the precise, not the approximate, choice.
Speed tricks and shortcuts
- Verbalise the relationship before scanning options.
- Make the rule as specific as possible to defeat close-fit traps.
- For classification, hunt the one shared property; the breaker is the answer.
- For number sets, test square/cube/prime/±/× patterns.
Settling for an option that fits a vague relationship. "Hand : Glove :: Foot : Sock" tempts because both are worn — but the exact link (outer covering) points to shoe. Always tighten the relationship until a single answer remains.
- ✓- Analogy = apply the same relationship to a new pair.
- ✓- Classification = find the shared rule; the odd one breaks it.
- ✓- State the relationship in words before answering.
- ✓- Make the rule specific to beat near-miss options.
- ✓- Test number sets for arithmetic patterns.
- ✓Analogy and classification are relationship-spotting drills. Name the link precisely, apply or break it consistently, and tighten the rule whenever two options tempt you. Precision converts these fast questions into certain marks.
Analogy and Classification — Worked Example
Worked Example
Problem: (i) Complete the analogy: 2 : 8 :: 3 : ?
(ii) Find the odd one out: 8, 27, 64, 100, 125.
Solution:
(i) Find the rule linking the first pair. 2 and 8: notice 2³ = 8, so the rule is "cube the number." Apply the same rule to 3:
3³ = 27.
So 2 : 8 :: 3 : 27.
(ii) Classification means finding the item that does not share the common property. Check whether each number is a perfect cube:
- 8 = 2³ ✓
- 27 = 3³ ✓
- 64 = 4³ ✓
- 125 = 5³ ✓
- 100 = 10², which is a perfect square, not a perfect cube ✗
Every number except 100 is a perfect cube, so 100 is the odd one out.
Answer: (i) 27; (ii) 100 (the only non-cube in the list).
- ✓- For analogies, first state the exact rule linking the given pair, then apply it.
- ✓- Common numerical rules: squares, cubes, doubling, +constant.
- ✓- In classification, identify the shared property; the exception is the odd one out.