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TNPSC Group II/IIA

Aptitude and Mental Ability — TNPSC Group II / IIA Guide

Complete aptitude and mental ability preparation guide for TNPSC Group II and IIA: all topics with solved examples, shortcuts, practice questions, and exam tips.

Updated 28 May 20267 min read

Overview

Aptitude and Mental Ability is the most predictable section in TNPSC Group II / IIA. Unlike GS (which has a vast syllabus), aptitude has a fixed set of topics. With 30 minutes of daily practice over 3–4 months, you can consistently score 80–90% in this section.

Topic-wise Breakdown

Arithmetic (Number-based Questions)

1. Number System
Answer
  • HCF and LCM
  • Divisibility rules (2, 3, 4, 5, 6, 8, 9, 11)
  • Prime numbers, composite numbers
  • Squares, cubes, square roots

Quick tip — Divisibility of 11: Sum of odd-position digits − Sum of even-position digits = 0 or multiple of 11 Example: 121 → (1+1) − 2 = 0 ✓ Divisible by 11

2. Percentage Formula: Percentage = (Part / Whole) × 100

TypeFormula
% increase(New − Old)/Old × 100
% decrease(Old − New)/Old × 100
x% of yxy/100

Example: If population increases from 5,000 to 5,500: Increase % = (500/5000) × 100 = 10%

3. Profit and Loss
Answer
TermFormula
ProfitSP − CP
LossCP − SP
Profit %(Profit/CP) × 100
SPCP × (1 + P%/100)

Example: CP = ₹800, SP = ₹920. Profit % = (120/800) × 100 = 15%

4. Simple and Compound Interest
Answer
  • SI = (P × R × T) / 100
  • CI = P × (1 + R/100)ⁿ − P

Example: SI on ₹2000 at 10% for 3 years = (2000 × 10 × 3)/100 = ₹600

5. Time, Speed and Distance
Answer
  • Speed = Distance / Time
  • 1 km/h = 5/18 m/s; 1 m/s = 18/5 km/h

Example: Train 300m long, speed 72 km/h = 20 m/s. Time to cross a pole = 300/20 = 15 seconds

Trains:

  • Pass a stationary object: Time = Train length / Train speed
  • Two trains (same direction): Relative speed = difference of speeds
  • Two trains (opposite direction): Relative speed = sum of speeds

6. Averages Average = Sum of all items / Number of items

Example: Average of 5, 10, 15, 20, 25 = 75/5 = 15

Weighted average (mixtures): If group A has average a and group B has average b, combined average = (n₁a + n₂b) / (n₁ + n₂)

7. Ratio and Proportion
Answer
  • Ratio a:b means a/b
  • Proportion: a:b = c:d → a×d = b×c (cross product)

Example: Divide ₹3600 in ratio 4:5. Total parts = 9. Share 1 = (4/9)×3600 = ₹1600, Share 2 = ₹2000

Verbal and Logical Reasoning

8. Number Series
Answer

Look for: Arithmetic (+n each time), Geometric (×n each time), Squares/Cubes, Mixed patterns

Examples:

  • 2, 4, 8, 16, __ → Pattern: ×2 → 32
  • 3, 9, 27, 81, __ → Pattern: ×3 → 243
  • 1, 4, 9, 16, 25, __ → Squares → 36
  • 2, 5, 10, 17, 26, __ → Differences: 3, 5, 7, 9, 11 → 37

9. Analogies (Word Relationships) Form: A : B :: C : ?

Common relationship types:

  • Object : Function (Pen : Writing :: Knife : Cutting)
  • Cause : Effect (Fire : Smoke :: Cloud : Rain)
  • Part : Whole (Leaf : Tree :: Petal : Flower)
  • Worker : Instrument (Carpenter : Saw :: Farmer : Plough)
10. Odd One Out
Answer

Look for: one item that doesn't belong to the same category as others

Example: Apple, Mango, Banana, Carrot → Carrot (vegetable, others are fruits) Example: Doctor, Teacher, Lawyer, Carpenter → Carpenter (manual trade vs. professional degree)

11. Coding and Decoding
Answer

Letter shift coding: APPLE → CRRNG (each letter +2) Number coding: A=1, B=2, C=3... OR A=26, B=25...

Example: If CAT = 24 (C=3, A=1, T=20; 3+1+20=24), then DOG = ? (D=4, O=15, G=7; 4+15+7=26)

12. Blood Relations
Answer

Standard relationships:

  • Father's/Mother's brother = Uncle
  • Father's/Mother's sister = Aunt
  • Son's wife = Daughter-in-law
  • Husband's/Wife's father = Father-in-law

Example: "A is the son of B. C is the daughter of A. How is C related to B?" → C is B's granddaughter

13. Direction and Distance
Answer

Cardinal directions: N, S, E, W + NE, NW, SE, SW

Tip: Always draw the path on scratch paper.

Example: Start → Walk 5km North → Turn Right → Walk 3km East → Turn Right → Walk 5km South → Final position: 3km East of start

14. Data Interpretation
Answer

Types: Bar graph, pie chart, line graph, table

Steps: 1. Read the title and axes carefully 2. Note the unit (thousands? lakhs? percentage?) 3. Answer only what is asked — don't over-calculate

15. Seating Arrangement / Ranking
Answer

Common question types:

  • "A is 5th from the left and 8th from the right. Total persons = 5 + 8 − 1 = 12"
  • Linear arrangement: Place all members based on given clues step by step

20 Quick Practice Questions

Q1. A train travels at 60 km/h. How far does it go in 2.5 hours? Ans: 60 × 2.5 = 150 km

Q2. If 20% of a number is 50, what is the number? Ans: 50/0.20 = 250

Q3. What is the next number: 1, 1, 2, 3, 5, 8, __? Ans: 13 (Fibonacci series)

Q4. Find the odd one out: Mercury, Venus, Earth, Moon Ans: Moon (natural satellite, not a planet)

Q5. P is taller than Q; R is shorter than P; S is taller than Q but shorter than R. Who is second tallest? Ans: P > R > S > Q → R is second tallest

Q6. If APPLE = 5, MANGO = 5, BANANA = 6, PINEAPPLE = ? Ans: Count letters — PINEAPPLE has 9 letters → 9

Q7. Find HCF of 36 and 48. Ans: Factors of 36 = 1,2,3,4,6,9,12,18,36; of 48 = 1,2,3,4,6,8,12,16,24,48. HCF = 12

Q8. Profit % if CP = ₹500 and SP = ₹600? Ans: (100/500) × 100 = 20%

Q9. The average of 6 numbers is 15. If one number is removed, average becomes 14. What was the removed number? Ans: Sum of 6 = 90; Sum of 5 = 70; Removed = 90 − 70 = 20

Q10. A man walks 4 km North, then 3 km East. Distance from start = ? Ans: √(4² + 3²) = √25 = 5 km (Pythagoras)

Q11. Find odd one out: 144, 121, 100, 90 Ans: 90 (others are perfect squares: 12², 11², 10²)

Q12. In a class of 40, if A ranks 12th from top, his rank from bottom = ? Ans: 40 − 12 + 1 = 29

Q13. Rate of simple interest if ₹1000 gives ₹300 interest in 3 years? Ans: SI = PRT/100 → 300 = 1000 × R × 3/100 → R = 10%

Q14. If 8 workers can build a wall in 10 days, how many days for 4 workers? Ans: 8 × 10 = 4 × D → D = 20 days

Q15. Complete the analogy: Square : 4 :: Pentagon : ? Ans: 5 (number of sides)

TNPSC Exam Tips — Aptitude

1. Solve without calculator daily — mental calculation speed is critical 2. Learn tables up to 20 — saves 10–15 seconds per question 3. Skip and return — if a question takes more than 1.5 minutes, mark and return later 4. Don't guess blindly — negative marking (1/3) punishes random guessing 5. Previous papers are key — TNPSC reuses question patterns; solve last 5 years' papers 6. Series questions first — these are the quickest wins in the aptitude section

Frequently Asked Questions

Approximately 25 questions (out of 200) carry about 37 marks. Aptitude is a highly scorable section — consistent daily practice for 30 minutes can get you 20+ out of 25 questions correct.