Practice questions

Aptitude practice questions (Group 4)

Questions 13 to 18 of 20

By TNPSC Guide editorial team · Last updated: 27.10.2026

1. Question 13

   What is the compound interest on ₹10000 at 8% compounded annually for the fractional period of 2¾ years?

   1. A. ₹2200
   2. B. ₹2363.84
   3. C. ₹12363.84
   4. D. ₹1664
   Answer and explanation

   Correct answer: B. ₹2363.84

   For a fractional period A = P(1 + r/100)ᵃ × (1 + (b/c) × r/100) = 10000 × (27/25)² × 53/50 = ₹12363.84; C.I = ₹2363.84.

   Source: கணக்கு, எட்டாம் வகுப்பு, தமிழ் வழி (Mathematics, Standard VIII, Tamil medium; Samacheer Kalvi) (இயல் 4 வாழ்வியல் கணிதம் (4.4 கூட்டுவட்டி), p. 142 (PDF p. 148))

2. Question 14

   Under compound interest, what happens to the interest earned in one period?

   1. A. It is subtracted from the principal
   2. B. It is worked out again on the first principal only
   3. C. It lowers the next year's rate of interest
   4. D. It is added to the principal, which becomes the principal for the next period
   Answer and explanation

   Correct answer: D. It is added to the principal, which becomes the principal for the next period

   In post offices and banks the interest of the first period is added to the principal, and that sum is the principal for the next period; this is compound interest.

   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))

3. Question 15

   Polishing costs ₹45 per sq m. What does it cost to polish 200 rhombus tiles with diagonals 40 cm and 25 cm?

   1. A. ₹450
   2. B. ₹45,00,000
   3. C. ₹45000
   4. D. ₹4500
   Answer and explanation

   Correct answer: A. ₹450

   One tile is ½ × 40 × 25 = 500 sq cm; 200 tiles make 100000 sq cm = 10 sq m (1 sq m = 10000 sq cm); the cost is 10 × 45 = ₹450.

   Source: கணக்கு, ஏழாம் வகுப்பு, முதல் பருவம், தொகுதி 2, தமிழ் வழி (Mathematics, Standard VII, Term I, Volume 2, Tamil medium; Samacheer Kalvi) (இயல் 2 அளவைகள், p. 44 (PDF p. 48))

4. Question 16

   What is the perimeter of a square of side a?

   1. A. a²
   2. B. 2a
   3. C. 4a
   4. D. 4a²
   Answer and explanation

   Correct answer: C. 4a

   A rectangle has perimeter 2(l + b) and area l × b; a square has perimeter 4a and area a × a.

   Source: கணக்கு, ஏழாம் வகுப்பு, முதல் பருவம், தொகுதி 2, தமிழ் வழி (Mathematics, Standard VII, Term I, Volume 2, Tamil medium; Samacheer Kalvi) (இயல் 2 அளவைகள், p. 34 (PDF p. 38))

5. Question 17

   Consider the following statements on packing boxes in a carton. 1. Large volume ÷ small volume is the upper limit on the number of boxes that can be packed. 2. If the three sides of the carton are divisible by the three sides of the box in some order, each by a different side, that number is packed exactly. 3. In the 1 m × 88 cm × 63 cm carton, one of 22, 18 and 10 cm divides 63 cm exactly. Which of these are correct?

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

   Correct answer: B. 1 and 2 only

   The quotient of the volumes is an upper limit; if the sides divide one to one, that number is packed exactly; but none of 22, 18 and 10 divides 63 (63 = 22 × 2 + 19 = 18 × 3 + 9 = 10 × 6 + 3); so 1 and 2 are correct and 3 is wrong.

   Source: கணக்கு, ஒன்பதாம் வகுப்பு, தமிழ் வழி (Mathematics, Standard IX, Tamil medium; Samacheer Kalvi) (இயல் 7 அளவியல் (7.5 கனச்செவ்வகம், கனச்சதுரத்தின் கனஅளவு), p. 275 (PDF p. 281))

6. Question 18

   How many edges does a cube have?

   1. A. 6
   2. B. 8
   3. C. 24
   4. D. 12
   Answer and explanation

   Correct answer: D. 12

   A cube has 6 faces, 12 edges and 8 vertices.

   Source: கணக்கு, எட்டாம் வகுப்பு, தமிழ் வழி (Mathematics, Standard VIII, Tamil medium; Samacheer Kalvi) (இயல் 2 அளவைகள் (2.4 முப்பரிமாண வடிவங்கள்), p. 69 (PDF p. 75))