CDS 2026 (I) Elementary Mathematics, question 15

Topic: Arithmetic (percentage, ratio, interest, time and work, speed)

Answers by SolvedPaper. UPSC has not released the official answer key for this paper yet. We will update it when they do.

Q15

12 men working 8 hours a day can completely build a wall of length 100 m, breadth 20 cm and height 5 m in 10 days. How many days will 16 men working 10 hours a day require to build a wall of length 200 m, breadth 60 cm and height 5 m ?

  1. (a) 1818
  2. (b) 2424
  3. (c) 2727
  4. (d) 3636Correct answer

Solution.

Answer: (d) 3636

  1. The new wall has 2×3×1=62 \times 3 \times 1 = 6 times the old volume.
  2. Daily labour capacity increases by (16×10)/(12×8)=5/3(16 \times 10)/(12 \times 8) = 5/3.
  3. Required days =10×6÷(5/3)=36= 10 \times 6 \div (5/3) = 36.