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Year 9 Simple and Compound Interest Worksheet — Level 3 — Practice Set 4 — 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 4 — Answers

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

1.$12,250.00 is invested at 4% per year, compounded yearly, for 8 years. Find the final amount and the interest earned, to the nearest cent.

Answer: Amount $16,764.97; interest $4,514.97

  1. A = P(1 + r)n = $12,250.00 × (1 + 0.04)8
  2. = $12,250.00 × 1.368569
  3. ≈ $16,764.97
  4. Interest = $16,764.97 − $12,250.00 = $4,514.97
2.$6,500.00 is invested at 2% per year, compounded yearly, for 4 years. Find the final amount and the interest earned, to the nearest cent.

Answer: Amount $7,035.81; interest $535.81

  1. A = P(1 + r)n = $6,500.00 × (1 + 0.02)4
  2. = $6,500.00 × 1.082432
  3. ≈ $7,035.81
  4. Interest = $7,035.81 − $6,500.00 = $535.81
3.Compare $2,500.00 invested for 6 years at 3% per year as simple interest and as interest compounded yearly. How much more does compound interest earn, to the nearest cent?

Answer: $35.13

  1. Simple: I = $2,500.00 × 0.03 × 6 = $450.00
  2. Compound: A = $2,500.00 × 1.036 ≈ $2,985.13, so interest ≈ $485.13
  3. Difference = $485.13 − $450.00 = $35.13
4.Compare $2,000.00 invested for 4 years at 4.5% per year as simple interest and as interest compounded yearly. How much more does compound interest earn, to the nearest cent?

Answer: $25.04

  1. Simple: I = $2,000.00 × 0.045 × 4 = $360.00
  2. Compound: A = $2,000.00 × 1.0454 ≈ $2,385.04, so interest ≈ $385.04
  3. Difference = $385.04 − $360.00 = $25.04
5.$7,250.00 is invested at 4% per year, compounded yearly, for 8 years. Find the final amount and the interest earned, to the nearest cent.

Answer: Amount $9,922.13; interest $2,672.13

  1. A = P(1 + r)n = $7,250.00 × (1 + 0.04)8
  2. = $7,250.00 × 1.368569
  3. ≈ $9,922.13
  4. Interest = $9,922.13 − $7,250.00 = $2,672.13
6.Compare $2,250.00 invested for 4 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: $91.10

  1. Simple: I = $2,250.00 × 0.08 × 4 = $720.00
  2. Compound: A = $2,250.00 × 1.084 ≈ $3,061.10, so interest ≈ $811.10
  3. Difference = $811.10 − $720.00 = $91.10
7.Compare $2,000.00 invested for 6 years at 3% per year as simple interest and as interest compounded yearly. How much more does compound interest earn, to the nearest cent?

Answer: $28.10

  1. Simple: I = $2,000.00 × 0.03 × 6 = $360.00
  2. Compound: A = $2,000.00 × 1.036 ≈ $2,388.10, so interest ≈ $388.10
  3. Difference = $388.10 − $360.00 = $28.10
8.$2,000.00 is invested at 4% per year, compounded yearly, for 7 years. Find the final amount and the interest earned, to the nearest cent.

Answer: Amount $2,631.86; interest $631.86

  1. A = P(1 + r)n = $2,000.00 × (1 + 0.04)7
  2. = $2,000.00 × 1.315932
  3. ≈ $2,631.86
  4. Interest = $2,631.86 − $2,000.00 = $631.86
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