Analogy

high importance~3 Q in Tier 112 formulas⚡ 11 shortcuts6 subtopics

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The idea of analogy

⏱ 5 min read🧩 5 question types🎯 12 practice Q

The idea in one minute

An analogy question gives one pair and asks you to copy its link. It is written A : B :: C : ?, read as "A is to B as C is to what?". You are not tested on facts about the words or numbers. You are tested on one skill: name the link exactly, then use it again in the same direction.

What the question asks

An analogy compares two pairs that share one link. Read the single colon ( : ) as "is to". Read the double colon ( :: ) as "as".

Teacher : School :: Doctor : Hospital. Both pairs say the same thing: a person and the place where the person works.

The question hides one term. You find the link in the full pair and use it to fill the gap.

Say the link as one sentence

This is the whole method. Use it on every analogy.

Say the link of the full pair as one short sentence.
Check the direction: which term comes first?
Use the same sentence, in the same direction, on the other pair.
Test all four options. Only one should make a true sentence.

Example: Cow : Calf :: Horse : ? The sentence is "the second is the young one of the first". A young horse is a foal. Mare is a trap: it is a female horse, not a young one.

Rule: Keep the direction. If the first pair goes adult → young, the answer pair must also go adult → young.

The five kinds you will meet

Kind	Example	What decides the answer
Word	Pen : Write :: Knife : Cut	meaning or use
Letter	ACE : BDF :: GIK : HJL	alphabet positions (+1 here)
Number	3 : 27 :: 5 : 125	an arithmetic rule (cube here)
Mixed	C5 : F10 :: H8 : K16	a letter rule and a number rule
Number set	(2, 4, 8) and (3, 9, 27)	one rule for all three numbers

Each kind has its own lesson. The method above works for all of them.

Where the blank can sit

At the end: A : B :: C : ? This is the most common form.
At the start or middle: ? : B :: C : D. Find the rule from the full pair. Then run it backwards. If 5 : 125 is "cube", then ? : 64 asks "which number cubed gives 64?" The answer is 4.
Three terms on each side: A : B : C :: D : E : ? One rule joins all three terms in order.
Two blanks: ? : B :: C : ? Each option gives two terms. Put both in and keep the option where both pairs share the link.
Two model pairs: A : B :: ? : D :: E : F. Two full pairs fix the rule. Find the rule, then fill the middle gap.
Pick a pair: "Select the pair related in the same way as X : Y." Test all four pairs with one sentence.

Tip: When the blank is on the left, undo the rule. Multiply becomes divide. Add becomes subtract. Square becomes square root.

Sharpen the sentence when two options fit

Setters put options from the same field on purpose. A loose sentence lets two of them through.

Take Thermometer : Temperature :: Odometer : ? The options are Distance, Speed, Kilometre and Car. All four are about vehicles.

A loose sentence: "related to travel". Too many options pass.
A sharp sentence: "an instrument and the quantity it measures". Only distance passes.
Speed is measured by a speedometer. A kilometre is only a unit of distance.

Watch: If two options still fit, add one more detail: male or female, young or adult, tool or product, unit or quantity.

Question types you will see

Each type: how to recognise it, the method step by step, and one question to try.

Type 1common4 practice Q

Missing term in the first or second place (? : B :: C : D)

How to spot it:

The question mark is not at the end, e.g. "? : 64 :: 5 : 125" or "Dog : ? :: Horse : Neigh".

A = f^{-1}(B)

Method

Find the rule from the complete pair.
Write it as a short equation or sentence.
Run it backwards to get the missing term.
Check your answer by running the rule forwards.

Why it works:

The link is the same in both pairs; only the position of the gap has moved.

Try this

Select the number that can replace the question mark. ? : 170 :: 11 : 122. (a) 12 (b) 13 (c) 14 (d) 15

Show solution

$11^2 = 121$ and $121 + 1 = 122$ . Rule: square, then add 1.
Backwards: $170 - 1 = 169$ .
$169 = 13^2$ , so the missing number is 13.

Answer

(b) 13

Type 2common3 practice Q

Close options: choose the exact relation

How to spot it:

All four options come from the same field (all instruments, all family words). Two or three look right at first.

Method

Write the link as a sharp sentence, not "related to".
Test each option with that sentence.
Reject units, tools, materials or places when the link needs a quantity, product or whole.

Why it works:

The setter places same-field options as traps; only the exact relation survives a sharp sentence.

Try this

Speedometer : Speed :: Ammeter : ? (a) Voltage (b) Ampere (c) Current (d) Circuit

Show solution

Link: an instrument and the quantity it measures.
An ammeter measures electric current.
Ampere is the unit of current, not the quantity. Voltage is measured by a voltmeter.

Answer

Type 3occasional2 practice Q

Three-term analogy (A : B : C :: D : E : ?)

How to spot it:

Each side has three terms, e.g. "2 : 4 : 8 :: 3 : 9 : ?".

a : a^2 : a^3

Method

Find how the 1st term becomes the 2nd.
Find how the 2nd becomes the 3rd (or how the 1st makes the 3rd).
Check the rule on the full group.
Apply the same steps to the second group.

Why it works:

Three terms fix the rule more firmly than two, so usually only one option fits.

Try this

Select the number that can replace the question mark. 5 : 26 : 126 :: 7 : 50 : ? (a) 343 (b) 344 (c) 350 (d) 345

Show solution

$26 = 5^2 + 1$ and $126 = 5^3 + 1$ .
Rule: $a,\ a^2 + 1,\ a^3 + 1$ .
Check: $7^2 + 1 = 50$ . Then $7^3 + 1 = 343 + 1 = 344$ .

Answer

(b) 344

Type 4occasional3 practice Q

Double blank: choose the pair that fills both blanks

How to spot it:

Two question marks, e.g. "? : Calf :: Horse : ?". Each option gives two terms.

Method

Put option 1 into both blanks.
Say the link of each pair.
Keep the option only if both links match, in the same direction.
Check the other options the same way.

Why it works:

A wrong option usually fits one blank but makes a different link in the other.

Try this

? : Puppy :: Cat : ? (a) Dog, Kitten (b) Kennel, Kitten (c) Dog, Mouse (d) Bitch, Tom

Show solution

(a) Dog : Puppy is adult : young. Cat : Kitten is adult : young. Both match.
(b) Kennel : Puppy is home : young. It does not match.
(c) and (d) give Cat : Mouse and Cat : Tom, which are not adult : young.

Answer

(a) Dog, Kitten

Type 5common

Two model pairs with a gap in the middle (A : B :: ? : D :: E : F)

How to spot it:

Three pairs are joined by "::" and the gap sits in the middle pair. The question says "in the same way as the second is related to the first and the sixth to the fifth".

B = f(A),\ F = f(E)

Method

Guess the rule from the first pair.
Confirm it on the last pair.
Run the rule backwards on D to fill the gap.

Why it works:

Two full pairs leave only one rule that fits both, so there is no guessing.

Try this

Select the number that can replace the question mark. 7 : 51 :: ? : 83 :: 11 : 123 (a) 8 (b) 9 (c) 10 (d) 12

Show solution

$7^2 + 2 = 51$ and $11^2 + 2 = 123$ . Rule: square, then add 2.
Backwards on 83: $83 - 2 = 81 = 9^2$ .

Answer

(b) 9

Shortcuts that save time

⚡ Say the link first, read the options second

Turn the full pair into a sentence before you look at the options. Then test each option with that same sentence. Options that are only from the same field fail the sentence at once.

Example

Doctor : Hospital :: ? (a) Teacher : Student (b) Judge : Court (c) Tailor : Cloth (d) Doctor : Medicine

Show solution

Sentence: "the second is the place where the first works".
Teacher : Student is a person, not a place. Tailor : Cloth is a material. Doctor : Medicine is a thing used.
Only a court is the place where a judge works.

Answer

(b) Judge : Court

Mistakes to avoid

Where most students lose marks on this subtopic.

Mistake 01

Picking an option because it is from the same topic (another animal, another instrument).

Pick the option that makes the same link sentence. Same topic is not enough.

Mistake 02

Reversing the direction: the model goes young → adult, the chosen pair goes adult → young.

Check which term comes first in the model pair and keep that order.

Mistake 03

Using one rule for the first pair and a slightly different rule for the second.

Write the rule once and use exactly that rule on the other pair.

Mistake 04

Stopping at the first option that looks right.

Test all four options. If two pass, make the sentence sharper.

Mistake 05

For ? : B :: C : D, applying the rule forwards to B.

When the blank is on the left, run the rule backwards (divide, subtract, take the root).

Quick revision

Read this the night before the exam.

":" means "is to"; "::" means "as".
Say the link as one sentence, then test all four options with it.
Keep the direction: the answer pair must go the same way as the model pair.
Blank on the left: run the rule backwards.
Three-term analogy: one rule links all three terms in order.
Two blanks: both pairs must share the same link.
Two options fit: sharpen the sentence (gender, age, tool, product, unit).

Practice: 12 questions

Sets of 10, mixed across the question types above. Every answer has a step-by-step explanation.

Topic test · 12 questions

Suggested time 9 min · wrong answers go to your mistake notebook automatically.

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