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WAEC Further Mathematics 2023 Question 10

Question 10

Sequences and Series

An exponential sequence (G.P.) is given by 9/2, 3/4, 1/8, …. Find its sum to infinity

  1. A.4⅕
  2. B.5⅖
  3. C.6¾
  4. D.13½
Show the answer and explanation

Answer: B (5⅖)

Explanation

r = (3/4) ÷ (9/2) = 1/6. S∞ = a/(1 − r) = (9/2) ÷ (5/6) = 27/5 = 5⅖.