Practice questions

Reasoning practice questions (Group 4)

Questions 12 to 16 of 20

By TNPSC Guide editorial team · Last updated: 27.10.2026

1. Question 12

   In a square, the midpoints of the four sides are joined in order (a rhombus), and the two midlines joining the midpoints of opposite sides are drawn. How many triangles are there in this figure?

   1. A. 8
   2. B. 12
   3. C. 16
   4. D. 4
   Answer and explanation

   Correct answer: B. 12

   4 triangles at the corners outside the rhombus; the midlines cut the rhombus into 4 small triangles; 4 more triangles each made of two neighbouring small ones; 4 + 4 + 4 = 12 (a systematic list of vertices also gives 12).

   Source: கணக்கு, ஆறாம் வகுப்பு, முதல் பருவம், தொகுதி 2, தமிழ் வழி (Mathematics, Standard VI, Term I, Volume 2, Tamil medium; Samacheer Kalvi) (இயல் 6 தகவல் செயலாக்கம் (பயிற்சி 6.1), p. 118 (PDF p. 122))

2. Question 13

   The midpoints of the three sides of a triangle are joined by straight lines. How many triangles are there in this figure altogether?

   1. A. 5
   2. B. 4
   3. C. 6
   4. D. 8
   Answer and explanation

   Correct answer: A. 5

   Joining the midpoints gives 4 small triangles; two or three of them together do not form a triangle; all four together form the big one; 4 + 1 = 5 in all.

   Source: கணக்கு, ஆறாம் வகுப்பு, முதல் பருவம், தொகுதி 2, தமிழ் வழி (Mathematics, Standard VI, Term I, Volume 2, Tamil medium; Samacheer Kalvi) (இயல் 6 தகவல் செயலாக்கம் (6.3.3 படத்திற்குள் பல படங்கள்), p. 117 (PDF p. 121))

3. Question 14

   A five-pointed star is drawn with five straight lines. How many small triangles are there at its points?

   1. A. 10
   2. B. 3
   3. C. 5
   4. D. 6
   Answer and explanation

   Correct answer: C. 5

   Each point is a small triangle; with five points there are 5 small triangles (a pentagon is left in the middle).

   Source: கணக்கு, ஆறாம் வகுப்பு, முதல் பருவம், தொகுதி 2, தமிழ் வழி (Mathematics, Standard VI, Term I, Volume 2, Tamil medium; Samacheer Kalvi) (இயல் 6 தகவல் செயலாக்கம் (6.3.3 படத்திற்குள் பல படங்கள்), p. 117 (PDF p. 121))

4. Question 15

   In the textbook's +4 table (e is A, f is B, ..., d is Z), which word is the secret fec?

   1. A. JIG
   2. B. CBZ
   3. C. AZX
   4. D. BAY
   Answer and explanation

   Correct answer: D. BAY

   4 places back: f → B, e → A; from c go b, a, then wrap to the end of the alphabet, z, y, so c → Y; fec is BAY.

   Source: கணக்கு, எட்டாம் வகுப்பு, தமிழ் வழி (Mathematics, Standard VIII, Tamil medium; Samacheer Kalvi) (இயல் 7 தகவல் செயலாக்கம் (7.7 குறியாக்கவியல்), p. 263 (PDF p. 269))

5. Question 16

   What is cryptology?

   1. A. A table that gives numbers to letters
   2. B. The science of communicating in a secure form
   3. C. A method of writing each word backwards
   4. D. A method of writing the alphabet backwards
   Answer and explanation

   Correct answer: B. The science of communicating in a secure form

   Cryptology is the science of communicating in a secure form; military, political and private communication all need information security.

   Source: கணக்கு, எட்டாம் வகுப்பு, தமிழ் வழி (Mathematics, Standard VIII, Tamil medium; Samacheer Kalvi) (இயல் 7 தகவல் செயலாக்கம் (7.7 குறியாக்கவியல்), p. 262 (PDF p. 268))