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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.$6,500.00 is invested at 6% per year, compounded yearly, for 9 years. Find the final amount and the interest earned, to the nearest cent.

Answer: Amount $10,981.61; interest $4,481.61

  1. A = P(1 + r)n = $6,500.00 × (1 + 0.06)9
  2. = $6,500.00 × 1.689479
  3. ≈ $10,981.61
  4. Interest = $10,981.61 − $6,500.00 = $4,481.61
2.$1,750.00 is invested at 5% per year, compounded yearly, for 3 years. Find the final amount and the interest earned, to the nearest cent.

Answer: Amount $2,025.84; interest $275.84

  1. A = P(1 + r)n = $1,750.00 × (1 + 0.05)3
  2. = $1,750.00 × 1.157625
  3. ≈ $2,025.84
  4. Interest = $2,025.84 − $1,750.00 = $275.84
3.Compare $14,500.00 invested for 4 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: $325.92

  1. Simple: I = $14,500.00 × 0.06 × 4 = $3,480.00
  2. Compound: A = $14,500.00 × 1.064 ≈ $18,305.92, so interest ≈ $3,805.92
  3. Difference = $3,805.92 − $3,480.00 = $325.92
4.$12,500.00 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 $18,503.05; interest $6,003.05

  1. A = P(1 + r)n = $12,500.00 × (1 + 0.04)10
  2. = $12,500.00 × 1.480244
  3. ≈ $18,503.05
  4. Interest = $18,503.05 − $12,500.00 = $6,003.05
5.Compare $1,500.00 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: $0.60

  1. Simple: I = $1,500.00 × 0.02 × 2 = $60.00
  2. Compound: A = $1,500.00 × 1.022 ≈ $1,560.60, so interest ≈ $60.60
  3. Difference = $60.60 − $60.00 = $0.60
6.$4,500.00 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 $6,399.45; interest $1,899.45

  1. A = P(1 + r)n = $4,500.00 × (1 + 0.045)8
  2. = $4,500.00 × 1.422101
  3. ≈ $6,399.45
  4. Interest = $6,399.45 − $4,500.00 = $1,899.45
7.$7,000.00 is invested at 2% per year, compounded yearly, for 5 years. Find the final amount and the interest earned, to the nearest cent.

Answer: Amount $7,728.57; interest $728.57

  1. A = P(1 + r)n = $7,000.00 × (1 + 0.02)5
  2. = $7,000.00 × 1.104081
  3. ≈ $7,728.57
  4. Interest = $7,728.57 − $7,000.00 = $728.57
8.$1,500.00 is invested at 3% per year, compounded yearly, for 9 years. Find the final amount and the interest earned, to the nearest cent.

Answer: Amount $1,957.16; interest $457.16

  1. A = P(1 + r)n = $1,500.00 × (1 + 0.03)9
  2. = $1,500.00 × 1.304773
  3. ≈ $1,957.16
  4. Interest = $1,957.16 − $1,500.00 = $457.16
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