Simple Interest worksheets - Free Printable

Of course! I'll solve each of these simple interest problems step by step and explain the solution.

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🔢 Simple Interest Formula:

The formula for Simple Interest is:

> I = P × r × t

Where:
- I = Interest earned
- P = Principal (starting amount)
- r = Annual interest rate (as a decimal)
- t = Time in years

Then, to find the ending balance, we add the interest to the principal:

> Ending Balance = P + I = P + (P × r × t) = P(1 + r × t)

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Let’s solve each problem one by one.

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✔ Problem 1: $450 at 7% for 2 years

- P = 450
- r = 7% = 0.07
- t = 2

I = 450 × 0.07 × 2 = 63

Ending Balance = 450 + 63 = $513

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✔ Problem 2: $12,000 at 2.2% for 5 years

- P = 12,000
- r = 2.2% = 0.022
- t = 5

I = 12,000 × 0.022 × 5 = 1,320

Ending Balance = 12,000 + 1,320 = $13,320

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✔ Problem 3: $1,300 at 5% for 6 years

- P = 1,300
- r = 5% = 0.05
- t = 6

I = 1,300 × 0.05 × 6 = 390

Ending Balance = 1,300 + 390 = $1,690

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✔ Problem 4: $1,300 at 5% for 6 years

*(This is identical to Problem 3)*

Ending Balance = $1,690

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✔ Problem 5: $5,400 at 3.5% for 6 months

⚠️ Important: Time must be in years.
6 months = 6/12 = 0.5 years

- P = 5,400
- r = 3.5% = 0.035
- t = 0.5

I = 5,400 × 0.035 × 0.5 = 94.50

Ending Balance = 5,400 + 94.50 = $5,494.50

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✔ Problem 6: $24,000 at 8.5% for 9 years

- P = 24,000
- r = 8.5% = 0.085
- t = 9

I = 24,000 × 0.085 × 9 = 18,360

Ending Balance = 24,000 + 18,360 = $42,360

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✔ Problem 7: $24,000 at 5.5% for 5 years

- P = 24,000
- r = 5.5% = 0.055
- t = 5

I = 24,000 × 0.055 × 5 = 6,600

Ending Balance = 24,000 + 6,600 = $30,600

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✔ Problem 8: $600 at 4% for 9 months

9 months = 9/12 = 0.75 years

- P = 600
- r = 4% = 0.04
- t = 0.75

I = 600 × 0.04 × 0.75 = 18

Ending Balance = 600 + 18 = $618

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✔ Problem 9: $5,400 at 7.5% for 6 months

6 months = 0.5 years

- P = 5,400
- r = 7.5% = 0.075
- t = 0.5

I = 5,400 × 0.075 × 0.5 = 202.50

Ending Balance = 5,400 + 202.50 = $5,602.50

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✔ Problem 10: $1,400 at 4.5% for 9 months

9 months = 0.75 years

- P = 1,400
- r = 4.5% = 0.045
- t = 0.75

I = 1,400 × 0.045 × 0.75 = 47.25

Ending Balance = 1,400 + 47.25 = $1,447.25

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## 📝 Final Answers:

1) $513
2) $13,320
3) $1,690
4) $1,690
5) $5,494.50
6) $42,360
7) $30,600
8) $618
9) $5,602.50
10) $1,447.25

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✔ All problems solved using the simple interest formula. Remember: time must always be in years — convert months by dividing by 12!

Let me know if you’d like to see the calculations written out differently or need help with compound interest next!