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JAMB Mathematics 1992 Question 13

Question 13

Commercial Arithmetic

A man invested the sum of N280.00 partly at 5% and partly at 4%. If the total interest is N12.80 per annum, find the amount invested at 5%.

  1. A.₦14.00
  2. B.₦120.00
  3. C.₦140.00
  4. D.₦160.00
Show the answer and explanation

Answer: D (₦160.00)

Explanation

Let x be at 5%: 0.05x + 0.04(280 − x) = 12.80, so 0.01x + 11.20 = 12.80 and x = ₦160.