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Year 9 Simple and Compound Interest Worksheet — Level 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 — Answers

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

1.Compare $8,250.00 invested for 8 years at 2.5% per year as simple interest and as interest compounded yearly. How much more does compound interest earn, to the nearest cent?

Answer: $151.82

  1. Simple: I = $8,250.00 × 0.025 × 8 = $1,650.00
  2. Compound: A = $8,250.00 × 1.0258 ≈ $10,051.82, so interest ≈ $1,801.82
  3. Difference = $1,801.82 − $1,650.00 = $151.82
2.Compare $12,250.00 invested for 8 years at 2% per year as simple interest and as interest compounded yearly. How much more does compound interest earn, to the nearest cent?

Answer: $142.83

  1. Simple: I = $12,250.00 × 0.02 × 8 = $1,960.00
  2. Compound: A = $12,250.00 × 1.028 ≈ $14,352.83, so interest ≈ $2,102.83
  3. Difference = $2,102.83 − $1,960.00 = $142.83
3.$11,000.00 is invested at 4.5% per year, compounded yearly, for 8 years. Find the final amount and the interest earned, to the nearest cent.

Answer: Amount $15,643.11; interest $4,643.11

  1. A = P(1 + r)n = $11,000.00 × (1 + 0.045)8
  2. = $11,000.00 × 1.422101
  3. ≈ $15,643.11
  4. Interest = $15,643.11 − $11,000.00 = $4,643.11
4.Compare $9,000.00 invested for 9 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: $312.96

  1. Simple: I = $9,000.00 × 0.03 × 9 = $2,430.00
  2. Compound: A = $9,000.00 × 1.039 ≈ $11,742.96, so interest ≈ $2,742.96
  3. Difference = $2,742.96 − $2,430.00 = $312.96
5.$9,500.00 is invested at 8% per year, compounded yearly, for 10 years. Find the final amount and the interest earned, to the nearest cent.

Answer: Amount $20,509.79; interest $11,009.79

  1. A = P(1 + r)n = $9,500.00 × (1 + 0.08)10
  2. = $9,500.00 × 2.158925
  3. ≈ $20,509.79
  4. Interest = $20,509.79 − $9,500.00 = $11,009.79
6.$13,750.00 is invested at 2% per year, compounded yearly, for 9 years. Find the final amount and the interest earned, to the nearest cent.

Answer: Amount $16,432.52; interest $2,682.52

  1. A = P(1 + r)n = $13,750.00 × (1 + 0.02)9
  2. = $13,750.00 × 1.195093
  3. ≈ $16,432.52
  4. Interest = $16,432.52 − $13,750.00 = $2,682.52
7.$6,250.00 is invested at 4% per year, compounded yearly, for 10 years. Find the final amount and the interest earned, to the nearest cent.

Answer: Amount $9,251.53; interest $3,001.53

  1. A = P(1 + r)n = $6,250.00 × (1 + 0.04)10
  2. = $6,250.00 × 1.480244
  3. ≈ $9,251.53
  4. Interest = $9,251.53 − $6,250.00 = $3,001.53
8.$7,500.00 is invested at 2% per year, compounded yearly, for 3 years. Find the final amount and the interest earned, to the nearest cent.

Answer: Amount $7,959.06; interest $459.06

  1. A = P(1 + r)n = $7,500.00 × (1 + 0.02)3
  2. = $7,500.00 × 1.061208
  3. ≈ $7,959.06
  4. Interest = $7,959.06 − $7,500.00 = $459.06
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