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JAMB Mathematics 1992 Question 18

Question 18

Progressions

Find the sum to the infinity of the following series 3 + 2 + 4/3 + 8/9 + 16/27 + ...

  1. A.1270
  2. B.190
  3. C.18
  4. D.9
Show the answer and explanation

Answer: D (9)

Explanation

It is a G.P. with a = 3 and r = ⅔. Sum to infinity = a/(1 − r) = 3/(⅓) = 9.