Analogy, Classification and Odd One Out Notes for Reasoning

Analogy and classification are among the most common and the easiest topics of the reasoning section in SSC, banking, railways, defence and state-level examinations. In analogy, you find the relationship between a given pair and apply the same relationship to another pair. In classification (odd one out), you find the item that does not belong to the group. Both test your ability to see relationships and patterns among words, letters and numbers. The questions are quick, and with a good method, each can be solved in 20 to 30 seconds. This note explains the types of relationships, a step-by-step method, solved examples for words, letters and numbers, and the common traps, in simple language.

What Is Analogy?

Analogy means similarity of relationship. A question is given in the form A : B :: C : ?, which is read as "A is to B as C is to ?". For example, in "Doctor : Hospital :: Teacher : ?", the doctor works in a hospital, so the teacher works in a school. The sign "::" means "in the same way as". Questions may also be in the form of "Which pair is related in the same way as the given pair?", with options of pairs.

A Four-Step Method for Analogy

1. Read the first pair carefully and find the exact relationship between the two words.
2. Make a short sentence using the relationship: "A is used for B" or "A is a part of B".
3. Apply the same sentence to the second pair and check each option.
4. If more than one option fits, make the relationship more specific (for example, "the place where the person works" instead of "related to").

Common Types of Word Relationships

Letter Analogy

In letter analogies, the relationship is based on the positions of letters in the alphabet (A = 1, B = 2, ... Z = 26). Find how the letters of the first group change into the second group (forward or backward shifts, reversals, or a pattern in the gaps), and apply the same change. Example: BD : FH :: JL : ? B (2) and D (4) become F (6) and H (8), a shift of +4 in each letter. So J (10) and L (12) become N (14) and P (16). The answer is NP. Another type is a word-based code, such as "CAT : DBU", where each letter is moved forward by one position, so "DOG" becomes "EPH". Learn the alphabet positions well, and remember that opposite letters add up to 27.

Number Analogy

In number analogies, the relationship may be squares, cubes, multiplication, addition or a combination. Example: 4 : 16 :: 5 : ? 16 is the square of 4, so the answer is 25. Another: 3 : 27 :: 4 : ? 27 is the cube of 3, so the answer is 64. Another: 6 : 42 :: 7 : ? 42 = 6 × 7 (n × (n + 1)), so the answer is 7 × 8 = 56. Try to check squares, cubes, doubles, multiplication by the next number, and the sum or the difference of digits. In pair-type questions, such as "Which pair is similar to 8 : 64?", the relationship may be that the second number is the square of the first (so 9 : 81 is the match).

What Is Classification (Odd One Out)?

Classification means grouping similar items. In a question, you are given four or five items, and one of them does not belong to the group because of a difference in its nature, property or pattern. The task is to find that odd item. The question may be about words, letters, numbers or pairs.

Method for Classification

1. Look for the common property shared by most of the items: category, use, shape, number property or position in the alphabet.
2. Find the item that breaks the pattern. Check at least two possible common properties, because some groups can be divided in more than one way.
3. Choose the most logical odd one and not just a different one.

Solved Examples on Classification

• Words: Apple, Mango, Banana, Potato. Potato is a vegetable (a root), while the others are fruits.
• Words: Square, Circle, Triangle, Cube. Cube is a three-dimensional solid; the others are two-dimensional figures.
• Words: Delhi, Mumbai, Kolkata, Ganga. Ganga is a river; the others are cities.
• Numbers: 3, 5, 7, 9, 11. The number 9 is not a prime; the others are prime numbers.
• Numbers: 16, 25, 36, 48. The number 48 is not a perfect square.
• Numbers: 121, 144, 169, 200. The number 200 is not a perfect square.
• Letters: ACE, GIK, MOQ, BDG. The first three have a gap of +2 between the letters (A-C-E), but BDG has gaps of +2 and +3, so BDG is the odd one.
• Pairs (words): Dog : Bark, Cat : Meow, Cow : Moo, Horse : Stable. The first three pairs show an animal and its sound, but Horse : Stable shows an animal and its shelter.
• Pairs (numbers): (2, 8), (3, 27), (4, 64), (5, 100). In the first three pairs, the second number is the cube of the first, but the cube of 5 is 125, so (5, 100) is the odd one.

Tips to Improve Speed and Accuracy

Build a strong vocabulary and general knowledge, because many analogies depend on facts: capitals, authors and books, inventors, scientific units and organs. Learn squares up to 25 and cubes up to 15, the first 15 primes and the alphabet positions. Always find the exact relationship, not a vague one; "Bird : Nest" is "animal and home", but "Bird : Fly" is "animal and action". Check all options before marking the answer. In classification, if two items seem different, ask which difference is stronger. If you are stuck, move on and return later. Practising 10 questions of each type daily for a week will make you very fast.

Common Traps

Some options are designed to look correct because they are related to the word, but they do not follow the same relationship. For example, for "Pen : Write", the pair "Paper : Book" is related in a different way (part and whole), so it does not match. In number analogies, a pair may fit one rule but not another; test the rule on all the given pairs. In letter analogies, forget the wrap-around from Z to A, and miscounting positions is a major source of error. In classification, avoid choosing an item just because it looks unusual; look for the logical reason.

Practice Questions With Answers

Try these: (1) Bird : Nest :: Bee : ? Answer: Hive. (2) Author : Book :: Painter : ? Answer: Painting. (3) Eye : See :: Ear : ? Answer: Hear. (4) 5 : 125 :: 6 : ? Answer: 216 (cube). (5) AZ : BY :: CX : ? Answer: DW (the first letter moves forward and the second moves backward). (6) Odd one out: Rose, Lotus, Jasmine, Mango. Answer: Mango (a fruit; the rest are flowers). (7) Odd one out: 2, 3, 5, 9, 11. Answer: 9 (not prime). (8) Odd one out: Cricket, Hockey, Football, Chess. Answer: Chess (an indoor board game; the others are outdoor team sports).

Quick Revision

• Analogy: find the relationship in the first pair, make a sentence and apply it to the second pair.
• Word, letter and number analogies; learn squares, cubes, primes and alphabet positions.
• Classification: find the common property of most items; the item that does not fit is the odd one.
• Check the exact relationship; avoid vague links.

Analogy and classification are about seeing connections. Practise daily, keep a notebook of relationships and revise your mistakes, and you will be able to solve these questions in seconds.

Related Notes to Read Next

Continue your preparation with these related notes from the same subject:

• Ranking, Order and Mathematical Operations Notes for Reasoning
• Puzzles Notes for Reasoning
• Statement and Assumptions Notes for Reasoning
• All Reasoning notes

Frequently Asked Questions (FAQ)

What is analogy in reasoning?

Analogy is a relationship between two things that is applied to another pair, in the form A : B :: C : ?, to find the item that completes the same relationship.

How do I solve analogy questions?

Find the exact relationship in the first pair, make a short sentence describing it and apply the same relationship to the second pair.

What are the types of analogy questions?

They include word analogy, letter analogy and number analogy, and also questions where you pick the pair that has the same relationship as the given pair.

What is classification or odd one out?

In classification questions, you must find the item that does not belong to a group because it differs in some property or pattern.

How do I find the odd one out among numbers?

Check properties such as prime, even or odd, perfect squares, cubes, multiples and digit patterns, and find the number that breaks the rule.

What is a letter analogy?

In a letter analogy, the relationship between two groups of letters is based on their positions in the alphabet, such as forward or backward shifts.

What is the sum of opposite letters in the alphabet?

The positions of letters opposite to each other from the two ends of the alphabet add up to 27, for example A and Z.

Why do analogies depend on general knowledge?

Many analogies use facts like capitals, authors, inventors and scientific units, so general knowledge helps in identifying the correct relationship.

What is a common mistake in analogy questions?

A common mistake is to choose an option that is merely related to the word but does not have the same relationship as the given pair.

How much time should I spend on analogy or classification?

Spend about 20 to 30 seconds on each question, and skip and return later if you are stuck.

What helps in solving number analogies?

Knowing squares, cubes, primes and simple operations such as n × (n + 1) helps in number analogies.

How can I improve in analogy and classification?

Practise daily with different types, build vocabulary and general knowledge, keep a notebook of relationships and review mistakes.