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

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

1.$9,750.00 is invested at 2.5% per year, compounded yearly, for 9 years. Find the final amount and the interest earned, to the nearest cent.

Answer: Amount $12,176.41; interest $2,426.41

  1. A = P(1 + r)n = $9,750.00 × (1 + 0.025)9
  2. = $9,750.00 × 1.248863
  3. ≈ $12,176.41
  4. Interest = $12,176.41 − $9,750.00 = $2,426.41
2.$14,750.00 is invested at 6% per year, compounded yearly, for 6 years. Find the final amount and the interest earned, to the nearest cent.

Answer: Amount $20,923.16; interest $6,173.16

  1. A = P(1 + r)n = $14,750.00 × (1 + 0.06)6
  2. = $14,750.00 × 1.418519
  3. ≈ $20,923.16
  4. Interest = $20,923.16 − $14,750.00 = $6,173.16
3.$4,250.00 is invested at 5% per year, compounded yearly, for 10 years. Find the final amount and the interest earned, to the nearest cent.

Answer: Amount $6,922.80; interest $2,672.80

  1. A = P(1 + r)n = $4,250.00 × (1 + 0.05)10
  2. = $4,250.00 × 1.628895
  3. ≈ $6,922.80
  4. Interest = $6,922.80 − $4,250.00 = $2,672.80
4.Compare $4,750.00 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: $66.75

  1. Simple: I = $4,750.00 × 0.03 × 6 = $855.00
  2. Compound: A = $4,750.00 × 1.036 ≈ $5,671.75, so interest ≈ $921.75
  3. Difference = $921.75 − $855.00 = $66.75
5.Compare $8,500.00 invested for 7 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: $73.83

  1. Simple: I = $8,500.00 × 0.02 × 7 = $1,190.00
  2. Compound: A = $8,500.00 × 1.027 ≈ $9,763.83, so interest ≈ $1,263.83
  3. Difference = $1,263.83 − $1,190.00 = $73.83
6.$10,000.00 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 $15,938.48; interest $5,938.48

  1. A = P(1 + r)n = $10,000.00 × (1 + 0.06)8
  2. = $10,000.00 × 1.593848
  3. ≈ $15,938.48
  4. Interest = $15,938.48 − $10,000.00 = $5,938.48
7.$2,750.00 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 $4,383.08; interest $1,633.08

  1. A = P(1 + r)n = $2,750.00 × (1 + 0.06)8
  2. = $2,750.00 × 1.593848
  3. ≈ $4,383.08
  4. Interest = $4,383.08 − $2,750.00 = $1,633.08
8.Compare $9,000.00 invested for 2 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: $22.50

  1. Simple: I = $9,000.00 × 0.05 × 2 = $900.00
  2. Compound: A = $9,000.00 × 1.052 ≈ $9,922.50, so interest ≈ $922.50
  3. Difference = $922.50 − $900.00 = $22.50
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