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JAMB Mathematics 2001 Question 15

Question 15

Progressions

A man saves N100.00 in his first year of work and each year saves N20.00 more than in the preceeding year. In how many years will he save N5,800.00?

  1. A.20 years
  2. B.29 years
  3. C.58 years
  4. D.100 years
Show the answer and explanation

Answer: A (20 years)

Explanation

This is an A.P. with a = 100, d = 20. Setting n/2[200 + 20(n − 1)] = 5800 gives n2 + 9n − 580 = 0, so n = 20.