Introduction to Analogy and Classification

What you will learn

You will learn to state the exact relationship in an analogy, keep its direction, and check a classification rule against every item. These topics are named in the RRB reasoning syllabus. This lesson does not predict how many questions will come from them.

An analogy asks you to preserve a relationship. Classification asks you to identify a shared property and the item that does not satisfy it. In “odd one out”, odd means different from the group; it does not necessarily mean an odd number.

1 Read the relation before the options

In A : B :: C : ?, read “A is related to B in the same way that C is related to the missing item.” Do not choose something merely because it is associated with C.

Use four steps:

1. Name the first relationship in a short sentence
2. Keep the same direction from the first item to the second
3. Test each answer choice using that sentence
4. Check the completed pair against the original pair

For example, “a pen is used for writing” is more useful than “a pen and writing are connected”. The first statement gives you a rule to test.

2 Worked example Tool and function

Pen : Writing :: Scissors : ?

A. Cutting B. Tailor C. Cloth D. Metal

Answer A, Cutting. The relationship is tool → usual function. Scissors are used for cutting. A tailor may use scissors, cloth may be cut by them, and metal may be a material from which they are made. Those associations are real, but they change the relationship to user, object acted upon, or material.

The lesson is not “choose the closest associated word”. Preserve the same relationship on both sides.

3 Direction and level of comparison

Direction changes the question. Page → book is part → whole; book → page is whole → part.

Worked example: Using the direct structural part–whole relation, Page : Book :: Petal : ?

A. Flower B. Garden C. Colour D. Fragrance

Answer A, Flower. A page is a structural part of a book; a petal is a structural part of a flower. A garden may contain flowers, but it is not the same immediate structural level. Colour and fragrance are properties, not the corresponding whole.

Now reverse the first pair: Book : Page :: Bicycle : ?

A. Road B. Wheel C. Travel D. Rider

Answer B, Wheel. The direction is now whole → part. A road is a place of use, travel is an activity, and a rider is a user. Keeping the arrow direction avoids these distractors.

4 Match the exact property

A relationship may identify a type, function, part, place or measurable property. Choose the relevant one from the first pair; do not use a fixed list mechanically.

Worked example: Square : Four sides :: Triangle : ?

A. Three sides B. Three corners C. A closed figure D. Four sides

Answer A, Three sides. The first pair names the number of sides. “Three corners” is also true of a triangle, but changes the selected property. “A closed figure” is true too, but does not preserve the numerical side-count relation.

In familiar workplace examples, treat the relationship as the usual role specified by the question, not a claim that every person works in only one place. If both school and college appear as answers to a teacher–workplace analogy with no further clue, the wording may not select one answer. Do not hide that ambiguity behind a vague “strongest rule”. A sound practice item must supply a distinguishing clue or revise its options.

5 Classification Test the whole group

In a four-item classification question, a proposed rule must group the intended three items and exclude the fourth. Finding one unusual feature in an item is not enough.

Worked example: Classify by whether the entry names a day of the week: Monday, March, Friday, Sunday.

March is different. Monday, Friday and Sunday are days of the week; March names a month. The rule has been checked against all four entries.

Worked example: Classify these plane figures by whether the boundary consists only of straight line segments: triangle, square, circle, pentagon.

The circle is different. The other three have boundaries made of straight line segments. “The triangle has three sides” identifies one item, but does not explain a common group containing the other three. Use a shared property, not an isolated description.

The same discipline applies to numbers and letters. For example, when the specified criterion is primality, 3, 5 and 11 are prime while 9 is composite. The next lesson develops numerical and alphabet rules in detail.

6 A short solving routine

For an analogy, write a label over an arrow: item → relation → partner. Keep both the label and direction unchanged for the new pair. For classification, write one sentence beginning “These three all…” and test it against every option.

Use the question’s stated criterion first. When the criterion is not stated, compare simple, relevant relationships supported by the entries and options. Do not invent a complicated rule solely to rescue an answer you guessed. If a practice question genuinely supports two answers under its wording, identify the missing clue rather than pretending one is logically forced.

Check your understanding

Attempt all six questions before reading the key.

1. Needle : Sewing :: Knife : ? Choose the option preserving tool → function.

A. Cutting B. Cook C. Kitchen D. Steel

2. Under the direct part–whole relation, Chapter : Book :: Room : ?

A. House B. Door C. Furniture D. Painting

3. Triangle : Three sides :: Hexagon : ? Preserve the named property.

A. Six sides B. Six corners C. A polygon D. Three sides

4. Classify by whether the entry names a month: April, August, Tuesday, December. Which is different?

A. April B. August C. Tuesday D. December

5. Using the stated criterion “prime number”, which differs: 2, 7, 13, 15?

A. 2 B. 7 C. 13 D. 15

6. A workplace analogy has “Teacher : ?” with both School and College as options and no further clue. What is the best diagnosis?

A. School is forced because it is shorter B. College is forced because it is larger C. Both fit the stated relation; the item needs a distinguishing clue D. Neither can be a workplace

Explained key

1. A — Cutting is the function. Cook is a user, kitchen a place and steel a material.
2. A — A chapter is part of a book and a room part of a house. Door reverses the direction toward a smaller part.
3. A — The chosen property is the number of sides, so six sides fits. The other true descriptions do not preserve that exact property.
4. C — Tuesday is a day of the week; the other three are months.
5. D — 15 has divisors 3 and 5 in addition to 1 and itself. 2 is prime even though it is even; parity is not the stated criterion.
6. C — Both can be workplaces for a teacher. Word length and size are invented criteria; a sound item must distinguish the answers.

Source and scope

RRB CEN 09/2025, §14.1, p. 28 lists analogies, similarities and differences, and classification. The examples and explanations here are original teaching material, not official previous-year questions.

Analogy

Write a labelled arrow: pen — used for → writing. Preserve the label and direction: scissors — used for → cutting. Scissors → tailor changes the label to “used by”, so it does not complete the same analogy.

Quick reference

Analogy and classification quick reference

• Analogy preserves a relation; classification tests a shared property
• Name the relation, keep direction, test each option, recheck the pair
• Association alone is not enough: user, tool, function and material are different relations
• Compare the same level: direct part/whole, type/category or named property
• For classification, check the rule against all four entries
• Use a stated criterion before any alternative feature
• Two supported answers mean a missing clue, not permission to invent a rule
• Number and letter rules are developed in the next lesson