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9th Grade Simple and Compound Interest Worksheet — Level 3 — Practice Set 2 — 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 — Practice Set 2 — Answers

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

1.$13,750.00 is invested at 3% per year, compounded yearly, for 8 years. Find the final amount and the interest earned, to the nearest cent.

Answer: Amount $17,418.09; interest $3,668.09

  1. A = P(1 + r)n = $13,750.00 × (1 + 0.03)8
  2. = $13,750.00 × 1.26677
  3. ≈ $17,418.09
  4. Interest = $17,418.09 − $13,750.00 = $3,668.09
2.Compare $12,000.00 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: $485.87

  1. Simple: I = $12,000.00 × 0.08 × 4 = $3,840.00
  2. Compound: A = $12,000.00 × 1.084 ≈ $16,325.87, so interest ≈ $4,325.87
  3. Difference = $4,325.87 − $3,840.00 = $485.87
3.$1,500.00 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 $1,591.81; interest $91.81

  1. A = P(1 + r)n = $1,500.00 × (1 + 0.02)3
  2. = $1,500.00 × 1.061208
  3. ≈ $1,591.81
  4. Interest = $1,591.81 − $1,500.00 = $91.81
4.Compare $9,750.00 invested for 5 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: $39.79

  1. Simple: I = $9,750.00 × 0.02 × 5 = $975.00
  2. Compound: A = $9,750.00 × 1.025 ≈ $10,764.79, so interest ≈ $1,014.79
  3. Difference = $1,014.79 − $975.00 = $39.79
5.Compare $1,500.00 invested for 5 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: $57.34

  1. Simple: I = $1,500.00 × 0.06 × 5 = $450.00
  2. Compound: A = $1,500.00 × 1.065 ≈ $2,007.34, so interest ≈ $507.34
  3. Difference = $507.34 − $450.00 = $57.34
6.Compare $3,250.00 invested for 3 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: $3.93

  1. Simple: I = $3,250.00 × 0.02 × 3 = $195.00
  2. Compound: A = $3,250.00 × 1.023 ≈ $3,448.93, so interest ≈ $198.93
  3. Difference = $198.93 − $195.00 = $3.93
7.Compare $11,750.00 invested for 3 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: $22.21

  1. Simple: I = $11,750.00 × 0.025 × 3 = $881.25
  2. Compound: A = $11,750.00 × 1.0253 ≈ $12,653.46, so interest ≈ $903.46
  3. Difference = $903.46 − $881.25 = $22.21
8.$6,500.00 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 $9,243.65; interest $2,743.65

  1. A = P(1 + r)n = $6,500.00 × (1 + 0.045)8
  2. = $6,500.00 × 1.422101
  3. ≈ $9,243.65
  4. Interest = $9,243.65 − $6,500.00 = $2,743.65
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