Analogy and classification for SSC CGL

Analogy and classification are two sides of one skill: spotting a relationship and applying it without drifting. In an analogy you find how two items are related and carry that relationship to a new pair. In classification you find what several items share and pick the one that doesn't belong.

They look easy, and most of the time they are. The marks are lost in the other cases, where two different rules seem to fit and you grab the first one you see. This guide is about doing it the careful way at full speed.

How they appear in SSC CGL

Both types appear in the General Intelligence and Reasoning section of Tier 1 and in the Reasoning module of Tier 2. The exact count changes from shift to shift, so don't plan around a fixed number. What stays constant is the format:

Figure-based analogies follow the same logic with shapes; see figural analogy.

Word relationships worth knowing

For numbers, the usual suspects are n², n³, n² ± 1, n³ ± 1, n(n + 1), digit sums and products, and consecutive primes. For letters, use positions (A = 1 to Z = 26), uniform shifts, reversals and opposite letters, whose positions add up to 27 (A–Z, B–Y, C–X).

The four-step method

1. Name the relationship in the first pair in a full sentence: "an anemometer measures wind speed", not "they are related to weather".
2. Test it on every other pair given, and on each option.
3. Look for a rival. Ask whether a second rule also fits. For numbers, check odd or even, square, cube, prime and multiples. For words, check category, function and material.
4. Pick the option that fits the exact relationship. If two options survive, the more specific relationship wins.

Six worked examples

1. Anemometer : Wind speed :: Hygrometer : ?
Options: (a) Rainfall (b) Air pressure (c) Temperature (d) Humidity

The relationship is "instrument : what it measures". A hygrometer measures humidity. Rainfall is measured by a rain gauge, air pressure by a barometer and temperature by a thermometer, so each wrong option is ruled out on the same rule. Answer: (d) Humidity.

2. Carpenter : Saw :: Surgeon : ?
Options: (a) Scalpel (b) Hospital (c) Stethoscope (d) Patient

"Worker : tool" allows both scalpel and stethoscope. Sharpen the rule: a saw is the carpenter's cutting tool. The surgeon's cutting tool is the scalpel. Hospital is a workplace and patient is a person served, so both are different relationships. Answer: (a) Scalpel.

3. 6 : 42 :: 9 : ? :: 11 : 132
Options: (a) 72 (b) 81 (c) 90 (d) 99

With one pair, 6 : 42 could be "multiply by 7". The second pair kills that rule: 132 ÷ 11 = 12, not 7. Now test n(n + 1): 6 × 7 = 42 and 11 × 12 = 132. Both fit. So 9 × 10 = 90, option (c). Notice that 72 (9 × 8) and 99 (9 × 11) are traps built from half-right rules.

4. ABC : ZYX :: DEF : ?
Options: (a) CBA (b) XWV (c) WVU (d) EFG

Each letter is replaced by its opposite: A (1) ↔ Z (26), B (2) ↔ Y (25), C (3) ↔ X (24). For DEF: D (4) ↔ W (23), E (5) ↔ V (22), F (6) ↔ U (21). Answer: (c) WVU.

A single letter pair can often be explained by a strange shift as well (here −1, −3, −5 would give CBA). SSC's intended rules are the standard ones, and the options decide. If both a standard and an odd rule produce answers among the options, re-read the question; usually a second pair settles it.

5. Find the odd one out: 169, 225, 289, 361

All four are perfect squares: 13², 15², 17², 19². Three are squares of primes; 15 is not prime. Now check rivals. All four are odd. The only one divisible by 5 is 225, the only one ending in 5 is 225, and the only one divisible by 3 is 225. Every rival property points to the same number. Answer: 225.

6. Find the odd one out: BDF, HJL, PRT, KMP

Write positions. BDF = 2, 4, 6 (gaps +2, +2). HJL = 8, 10, 12 (+2, +2). PRT = 16, 18, 20 (+2, +2). KMP = 11, 13, 16 (+2, +3). Rival check: none of the four contains a vowel, so vowels don't separate them. Answer: KMP.

Classification: the category trap

Word classification fails when a set has two possible "odd" items. Take Rose, Lotus, Jasmine, Mango. Mango is the only fruit, but lotus is the only water plant. A well-set question avoids this. When you meet one like it, choose the most basic category the examiner is likely to mean (here, flower vs fruit), and don't burn a minute on it.

The same goes for numbers. In 49, 63, 77, 91, 102, the number 102 is the only one not divisible by 7, but 49 is the only perfect square. If both appear as options, the question is flawed. In the exam, go with the property that covers all the other items (multiples of 7 here), since that is what classification tests.

Common mistakes

Practice

1. Pen : Write :: Knife : ?
   • (a) Sharp (b) Kitchen (c) Steel (d) Cut
2. 2 : 9 :: 4 : 65 :: 5 : ?
   • (a) 124 (b) 125 (c) 126 (d) 130
3. BDFH : CEGI :: JLNP : ?
   • (a) KMOQ (b) KLMN (c) IKMO (d) LNPR
4. FAN : UZM :: CUP : ?
   • (a) XEK (b) XFK (c) DVQ (d) WFK
5. Find the odd one out: 29, 37, 51, 53
6. Find the odd one out: AZ, CX, EV, GS
7. Find the odd one out: Thermometer, Barometer, Hygrometer, Microscope
8. Cow : Calf :: Horse : ?
   • (a) Pony (b) Foal (c) Stallion (d) Mare

Answers

1. (d) Cut. Tool : function. "Sharp" is a quality, not what the tool does.
2. (c) 126. The rule is n³ + 1: 2³ + 1 = 9, 4³ + 1 = 65, so 5³ + 1 = 126.
3. (a) KMOQ. Every letter moves +1: J→K, L→M, N→O, P→Q.
4. (b) XFK. Opposite letters: F (6) ↔ U (21), A ↔ Z, N (14) ↔ M (13). So C (3) ↔ X (24), U (21) ↔ F (6), P (16) ↔ K (11).
5. 51. It equals 3 × 17; the others are prime. All four are odd, so parity doesn't compete.
6. GS. AZ, CX and EV are opposite pairs (positions add to 27). G (7) + S (19) = 26.
7. Microscope. The other three measure a quantity; a microscope magnifies.
8. (b) Foal. A foal is a young horse, as a calf is a young cow. A pony is a small breed, a stallion an adult male and a mare an adult female.

What to do next

1. Write the A1 to Z26 table and the opposite pairs from memory until it takes under a minute.
2. Solve 20 mixed analogy and classification questions a day for a week, with the rival check on every one.
3. Log each mistake as "wrong relationship", "rival rule" or "miscount". The biggest column tells you what to fix.
4. Move on to number and letter series, which uses the same position and pattern skills, then coding and decoding.