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WAEC Further Mathematics 2017 Question 25

Question 25

Sequences and Series

The 3rd and 7th terms of a Geometric Progression (G.P) are 81 and 16 respectively. Find the 5th term.

  1. A.4/729
  2. B.16/81
  3. C.27
  4. D.36
Show the answer and explanation

Answer: D (36)

Explanation

r⁴ = 16/81, so r² = 4/9. T₅ = T₃ × r² = 81 × 4/9 = 36.