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WAEC Further Mathematics 2006 Question 13

Question 13

Sequences and Series

Find the sum of the exponential series 96 + 24 + 6 + ..

  1. A.144
  2. B.128
  3. C.72
  4. D.64
Show the answer and explanation

Answer: B (128)

Explanation

This is a geometric series with a = 96 and r = ¼. Sum to infinity = a/(1 − r) = 96 ÷ ¾ = 128.