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Year 9 Simple and Compound Interest Worksheet — Level 3 — Practice Set 3 — Answers

Answer sheet with worked solutions for the Year 9 financial mathematics worksheet.

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Success TutoringWorksheetsAnswer sheetYear 9 · Mathematics · Financial Mathematics

Year 9 Simple and Compound Interest Worksheet — Level 3 — Practice Set 3 — Answers

Show your working. Write the rate as a decimal (5% = 0.05). Round money to the nearest cent.

1.Compare $12,250.00 invested for 9 years at 8% per year as simple interest and as interest compounded yearly. How much more does compound interest earn, to the nearest cent?

Answer: $3,417.81

  1. Simple: I = $12,250.00 × 0.08 × 9 = $8,820.00
  2. Compound: A = $12,250.00 × 1.089 ≈ $24,487.81, so interest ≈ $12,237.81
  3. Difference = $12,237.81 − $8,820.00 = $3,417.81
2.$12,000.00 is invested at 3% per year, compounded yearly, for 6 years. Find the final amount and the interest earned, to the nearest cent.

Answer: Amount $14,328.63; interest $2,328.63

  1. A = P(1 + r)n = $12,000.00 × (1 + 0.03)6
  2. = $12,000.00 × 1.194052
  3. ≈ $14,328.63
  4. Interest = $14,328.63 − $12,000.00 = $2,328.63
3.Compare $10,250.00 invested for 10 years at 6% per year as simple interest and as interest compounded yearly. How much more does compound interest earn, to the nearest cent?

Answer: $1,956.19

  1. Simple: I = $10,250.00 × 0.06 × 10 = $6,150.00
  2. Compound: A = $10,250.00 × 1.0610 ≈ $18,356.19, so interest ≈ $8,106.19
  3. Difference = $8,106.19 − $6,150.00 = $1,956.19
4.Compare $3,750.00 invested for 5 years at 8% per year as simple interest and as interest compounded yearly. How much more does compound interest earn, to the nearest cent?

Answer: $259.98

  1. Simple: I = $3,750.00 × 0.08 × 5 = $1,500.00
  2. Compound: A = $3,750.00 × 1.085 ≈ $5,509.98, so interest ≈ $1,759.98
  3. Difference = $1,759.98 − $1,500.00 = $259.98
5.$3,000.00 is invested at 8% per year, compounded yearly, for 2 years. Find the final amount and the interest earned, to the nearest cent.

Answer: Amount $3,499.20; interest $499.20

  1. A = P(1 + r)n = $3,000.00 × (1 + 0.08)2
  2. = $3,000.00 × 1.1664
  3. ≈ $3,499.20
  4. Interest = $3,499.20 − $3,000.00 = $499.20
6.$3,250.00 is invested at 6% per year, compounded yearly, for 2 years. Find the final amount and the interest earned, to the nearest cent.

Answer: Amount $3,651.70; interest $401.70

  1. A = P(1 + r)n = $3,250.00 × (1 + 0.06)2
  2. = $3,250.00 × 1.1236
  3. ≈ $3,651.70
  4. Interest = $3,651.70 − $3,250.00 = $401.70
7.Compare $1,250.00 invested for 9 years at 5% per year as simple interest and as interest compounded yearly. How much more does compound interest earn, to the nearest cent?

Answer: $126.66

  1. Simple: I = $1,250.00 × 0.05 × 9 = $562.50
  2. Compound: A = $1,250.00 × 1.059 ≈ $1,939.16, so interest ≈ $689.16
  3. Difference = $689.16 − $562.50 = $126.66
8.$14,750.00 is invested at 6% per year, compounded yearly, for 4 years. Find the final amount and the interest earned, to the nearest cent.

Answer: Amount $18,621.54; interest $3,871.54

  1. A = P(1 + r)n = $14,750.00 × (1 + 0.06)4
  2. = $14,750.00 × 1.262477
  3. ≈ $18,621.54
  4. Interest = $18,621.54 − $14,750.00 = $3,871.54
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