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9th Grade Simple and Compound Interest Worksheet — Level 3 — Answers

Answer sheet with worked solutions for the 9th Grade financial math worksheet.

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Success TutoringWorksheetsAnswer sheet9th Grade · Mathematics · Financial Mathematics

9th Grade Simple and Compound Interest Worksheet — Level 3 — Answers

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

1.Compare $11,500.00 invested for 9 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: $274.42

  1. Simple: I = $11,500.00 × 0.025 × 9 = $2,587.50
  2. Compound: A = $11,500.00 × 1.0259 ≈ $14,361.92, so interest ≈ $2,861.92
  3. Difference = $2,861.92 − $2,587.50 = $274.42
2.$13,250.00 is invested at 2.5% per year, compounded yearly, for 2 years. Find the final amount and the interest earned, to the nearest cent.

Answer: Amount $13,920.78; interest $670.78

  1. A = P(1 + r)n = $13,250.00 × (1 + 0.025)2
  2. = $13,250.00 × 1.050625
  3. ≈ $13,920.78
  4. Interest = $13,920.78 − $13,250.00 = $670.78
3.Compare $14,750.00 invested for 2 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: $5.90

  1. Simple: I = $14,750.00 × 0.02 × 2 = $590.00
  2. Compound: A = $14,750.00 × 1.022 ≈ $15,345.90, so interest ≈ $595.90
  3. Difference = $595.90 − $590.00 = $5.90
4.Compare $10,500.00 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: $193.23

  1. Simple: I = $10,500.00 × 0.025 × 8 = $2,100.00
  2. Compound: A = $10,500.00 × 1.0258 ≈ $12,793.23, so interest ≈ $2,293.23
  3. Difference = $2,293.23 − $2,100.00 = $193.23
5.Compare $1,000.00 invested for 10 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: $358.92

  1. Simple: I = $1,000.00 × 0.08 × 10 = $800.00
  2. Compound: A = $1,000.00 × 1.0810 ≈ $2,158.92, so interest ≈ $1,158.92
  3. Difference = $1,158.92 − $800.00 = $358.92
6.$11,500.00 is invested at 6% per year, compounded yearly, for 8 years. Find the final amount and the interest earned, to the nearest cent.

Answer: Amount $18,329.25; interest $6,829.25

  1. A = P(1 + r)n = $11,500.00 × (1 + 0.06)8
  2. = $11,500.00 × 1.593848
  3. ≈ $18,329.25
  4. Interest = $18,329.25 − $11,500.00 = $6,829.25
7.Compare $8,000.00 invested for 6 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: $320.77

  1. Simple: I = $8,000.00 × 0.05 × 6 = $2,400.00
  2. Compound: A = $8,000.00 × 1.056 ≈ $10,720.77, so interest ≈ $2,720.77
  3. Difference = $2,720.77 − $2,400.00 = $320.77
8.Compare $2,500.00 invested for 4 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: $6.08

  1. Simple: I = $2,500.00 × 0.02 × 4 = $200.00
  2. Compound: A = $2,500.00 × 1.024 ≈ $2,706.08, so interest ≈ $206.08
  3. Difference = $206.08 − $200.00 = $6.08
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