Practice questions

Aptitude practice questions (Group 4)

Questions 6 to 12 of 20

By TNPSC Guide editorial team · Last updated: 27.10.2026

1. Question 6

   In one class 32 of 40 pupils took part in a contest, and in another class 42 of 50. Consider the following statements. 1. The first class took part at 80% and the second at 84%. 2. The second class is ahead by 4 percentage points. 3. A rise from 80 to 84 is a 4% rise on 80. Which of these are correct?

   1. A. 1 only
   2. B. 1 and 3 only
   3. C. 1, 2 and 3
   4. D. 1 and 2 only
   Answer and explanation

   Correct answer: D. 1 and 2 only

   32/40 × 100 = 80% and 42/50 × 100 = 84%; the gap is 4 percentage points (the book, p. 127, calls it "4% more"); but a rise from 80 to 84 is 4/80 × 100 = 5%, not 4%; so 1 and 2 are correct and 3 is wrong.

   Source: கணக்கு, எட்டாம் வகுப்பு, தமிழ் வழி (Mathematics, Standard VIII, Tamil medium; Samacheer Kalvi) (இயல் 4 வாழ்வியல் கணிதம், p. 127 (PDF p. 133))

2. Question 7

   Find the HCF of 396, 504 and 636.

   1. A. 36
   2. B. 6
   3. C. 24
   4. D. 12
   Answer and explanation

   Correct answer: D. 12

   First the HCF of two: 504 = 396 × 1 + 108, 396 = 108 × 3 + 72, 108 = 72 × 1 + 36, 72 = 36 × 2 + 0, so (396, 504) = 36; then 636 = 36 × 17 + 24, 36 = 24 × 1 + 12, 24 = 12 × 2 + 0, so the HCF is 12.

   Source: கணிதம், பத்தாம் வகுப்பு, தமிழ் வழி (Mathematics, Standard X, Tamil medium; Samacheer Kalvi) (இயல் 2 எண்களும் தொடர்வரிசைகளும், pp. 42-43 (PDF pp. 48-49))

3. Question 8

   By what other name is the highest common factor (HCF) known?

   1. A. Greatest common divisor
   2. B. Least common multiple
   3. C. Prime factor
   4. D. Co-prime number
   Answer and explanation

   Correct answer: A. Greatest common divisor

   The largest number that divides the given numbers exactly is the HCF; it is also called the greatest common divisor (GCD).

   Source: கணக்கு, எட்டாம் வகுப்பு, தமிழ் வழி (Mathematics, Standard VIII, Tamil medium; Samacheer Kalvi) (இயல் 7 தகவல் செயலாக்கம் (7.6 மீப்பெரு பொதுக் காரணி), p. 259 (PDF p. 265))

4. Question 9

   Which of the following ratios is the greatest?

   1. A. 2 : 3
   2. B. 5 : 8
   3. C. 3 : 4
   4. D. 7 : 12
   Answer and explanation

   Correct answer: C. 3 : 4

   Write the ratios as fractions over the common denominator 24: 2/3 = 16/24, 3/4 = 18/24, 5/8 = 15/24, 7/12 = 14/24; so 3 : 4 is the greatest.

   Source: கணக்கு, ஆறாம் வகுப்பு, முதல் பருவம், தொகுதி 2, தமிழ் வழி (Mathematics, Standard VI, Term I, Volume 2, Tamil medium; Samacheer Kalvi) (இயல் 3 விகிதம் மற்றும் விகித சமம், pp. 54-55 (PDF pp. 58-59))

5. Question 10

   A ratio compares two quantities of what kind?

   1. A. Quantities of the same kind
   2. B. Quantities of different kinds
   3. C. Lengths only
   4. D. Fractions only
   Answer and explanation

   Correct answer: A. Quantities of the same kind

   A ratio compares two quantities of the same kind by saying how many times one is of the other; comparing quantities of different kinds is meaningless.

   Source: கணக்கு, ஆறாம் வகுப்பு, முதல் பருவம், தொகுதி 2, தமிழ் வழி (Mathematics, Standard VI, Term I, Volume 2, Tamil medium; Samacheer Kalvi) (இயல் 3 விகிதம் மற்றும் விகித சமம், p. 48 (PDF p. 52))

6. Question 11

   The difference between the compound and simple interest on a sum at 2% a year for 2 years is ₹1. What is the principal?

   1. A. ₹50
   2. B. ₹250
   3. C. ₹5000
   4. D. ₹2500
   Answer and explanation

   Correct answer: D. ₹2500

   For two years C.I − S.I = P(r/100)²: P × (2/100)² = 1, so P × 0.0004 = 1 and P = ₹2500.

   Source: கணக்கு, எட்டாம் வகுப்பு, தமிழ் வழி (Mathematics, Standard VIII, Tamil medium; Samacheer Kalvi) (விடைகள் (பயிற்சி 4.3), p. 286 (PDF p. 292))

7. Question 12

   What is the formula for simple interest I? (P principal, N years, R annual rate)

   1. A. I = PNR
   2. B. I = PNR/100
   3. C. I = P(1 + R/100)ᴺ
   4. D. I = 100PN/R
   Answer and explanation

   Correct answer: B. I = PNR/100

   Simple interest I = PNR/100, where P is the principal, N the number of years and R the annual rate.

   Source: கணக்கு, எட்டாம் வகுப்பு, தமிழ் வழி (Mathematics, Standard VIII, Tamil medium; Samacheer Kalvi) (இயல் 4 வாழ்வியல் கணிதம் (4.4 கூட்டுவட்டி), p. 139 (PDF p. 145))