Let's solve each of these
simple interest problems step by step.
The formula for
Simple Interest (SI) is:
$$
\text{Simple Interest} = P \times r \times t
$$
Where:
- $ P $ = Principal amount (initial amount)
- $ r $ = Annual interest rate (as a decimal)
- $ t $ = Time in years
We'll calculate the simple interest for each case.
---
1. A principal of $2,000 at a rate of 5% for 4 years.
$$
SI = 2000 \times 0.05 \times 4 = 2000 \times 0.2 = 400
$$
✔ $400
---
2. A principal of 900 Euros at a rate of 3% for 2 years.
$$
SI = 900 \times 0.03 \times 2 = 900 \times 0.06 = 54
$$
✔ 54 Euros
---
3. A principal of 1,200 Pounds at a rate of 9% for 11 years.
$$
SI = 1200 \times 0.09 \times 11 = 1200 \times 0.99 = 1188
$$
✔ 1,188 Pounds
---
4. A principal of 10,000 Baht at a rate of 7% for 5 years.
$$
SI = 10000 \times 0.07 \times 5 = 10000 \times 0.35 = 3500
$$
✔ 3,500 Baht
---
5. A principal of 4,000 Yen at a rate of 15% for 40 years.
$$
SI = 4000 \times 0.15 \times 40 = 4000 \times 6 = 24,000
$$
✔ 24,000 Yen
---
6. A principal of 2,500 Francs at a rate of 1.5% for 6 years.
$$
SI = 2500 \times 0.015 \times 6 = 2500 \times 0.09 = 225
$$
✔ 225 Francs
---
7. A principal of 900 Yuan at a rate of 3.5% for 4 years.
$$
SI = 900 \times 0.035 \times 4 = 900 \times 0.14 = 126
$$
✔ 126 Yuan
---
8. A principal of 8,000 Pesos at a rate of 5% for 5 years.
$$
SI = 8000 \times 0.05 \times 5 = 8000 \times 0.25 = 2000
$$
✔ 2,000 Pesos
---
9. A principal of 2,000 Reals at a rate of 5% for 2 years.
$$
SI = 2000 \times 0.05 \times 2 = 2000 \times 0.1 = 200
$$
✔ 200 Reals
---
10. A principal of 100,000 Kip at a rate of 3% for 4 years.
$$
SI = 100000 \times 0.03 \times 4 = 100000 \times 0.12 = 12,000
$$
✔ 12,000 Kip
---
11. A principal of 7,500 Euros at a rate of 9% for 4 years.
$$
SI = 7500 \times 0.09 \times 4 = 7500 \times 0.36 = 2,700
$$
✔ 2,700 Euros
---
✔ Final Answers (Summary):
| Problem | Simple Interest |
|--------|------------------|
| 1 | $400 |
| 2 | 54 Euros |
| 3 | 1,188 Pounds |
| 4 | 3,500 Baht |
| 5 | 24,000 Yen |
| 6 | 225 Francs |
| 7 | 126 Yuan |
| 8 | 2,000 Pesos |
| 9 | 200 Reals |
| 10 | 12,000 Kip |
| 11 | 2,700 Euros |
---
🔍 Explanation:
- The
simple interest does not compound — it’s calculated only on the original principal.
- We converted percentages to decimals (e.g., 5% → 0.05).
- Multiply: Principal × Rate × Time → gives total interest earned.
Let me know if you'd like the
total amount (principal + interest) instead!
Parent Tip: Review the logic above to help your child master the concept of simple interest word problems worksheet.
