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OAU Post-UTME Mathematics 2017 (Set 1 Type 1) Question 9

Question 9

Progressions

If the three consecutive terms of a GP are n − 2, n and n + 3, find the common ratio

  1. A.¼
  2. B.½
  3. C.¾
  4. D.1½
Show the answer and explanation

Answer: D (1½)

Explanation

n/(n − 2) = (n + 3)/n gives n² = n² + n − 6, so n = 6. The terms are 4, 6, 9 and the ratio is 6/4 = 1½.