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WAEC Further Mathematics 2009 Question 13

Question 13

Sequences and Series

The first term of a geometric series is 350. If the sum to infinity is 250, Find the common ratio.

  1. A.−5/7
  2. B.−2/5
  3. C.2/5
  4. D.5/7
Show the answer and explanation

Answer: B (−2/5)

Explanation

S∞ = a/(1 − r): 250 = 350/(1 − r), so 1 − r = 7/5 and r = −2/5.