passwella.
Menu

UI Post-UTME Mathematics 2025 (Model questions) Question 7

Question 7

Progressions

The first 10 terms of an arithmetic progression sum to 185 while the first 5 terms sum to 65. Find the common difference

  1. A.2/3
  2. B.11/2
  3. C.11/5
  4. D.3
Show the answer and explanation

Answer: C (11/5)

Explanation

S₅ = 65 gives a + 2d = 13; S₁₀ = 185 gives 2a + 9d = 37. Then 2(13 − 2d) + 9d = 37, so 5d = 11 and d = 11/5.