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0580/43 May/Jun 2026, Question 19: Simple Interest

Cambridge IGCSE Mathematics 0580 · Paper 43 (Extended) · Calculator · 9 marks

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The question, in short

Compare simple and compound interest investments and an exponential growth rate: find a final value, a number of years to exceed a target, and an annual percentage rate.

Summarised in our own words. Use the official paper for the exact wording and any diagrams.

Part (a) · 3 marks

Calculate the total value of $2000 at 3.5% simple interest after 4 years.

  1. 1Interest per year = 2000 × 0.035 = $70
  2. 2Interest for 4 years = 70 × 4 = $280
  3. 3Total = 2000 + 280 = $2280

Answer2280

Part (b) · 3 marks

Find how many complete years $3000 at 3.2% compound interest takes to exceed $4800.

  1. 1Need 3000 × 1.032ⁿ > 4800
  2. 23000 × 1.032¹⁴ = 4662.… (not enough)
  3. 33000 × 1.032¹⁵ = 4811.… (greater than 4800)
  4. 4n = 15 years

Answer15

Part (c) · 3 marks

Given a 19.4% increase over 6 years of exponential growth, find the annual rate r%.

  1. 1(1 + r/100)⁶ = 1.194
  2. 21 + r/100 = ⁶√1.194 = 1.0299…
  3. 3r = 2.999… = 3

Answer3 or 2.999…

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