Simple Interest worksheets - Free Printable

To solve these problems, we will use the formula for simple interest:

\[
\text{Simple Interest (SI)} = P \times r \times t
\]

Where:
- \( P \) is the principal amount (initial amount of money),
- \( r \) is the annual interest rate (in decimal form),
- \( t \) is the time the money is invested or borrowed for (in years).

The ending balance (or total amount) can be calculated as:

\[
\text{Ending Balance} = P + \text{SI}
\]

Let's solve each problem step by step.

---

1. $35,100 at 4% for 3 years

- \( P = 35,100 \)
- \( r = 4\% = 0.04 \)
- \( t = 3 \) years

\[
\text{SI} = P \times r \times t = 35,100 \times 0.04 \times 3 = 4,212
\]

\[
\text{Ending Balance} = P + \text{SI} = 35,100 + 4,212 = 39,312
\]

Answer: $39,312

---

2. $150 at 5% for 2 years

- \( P = 150 \)
- \( r = 5\% = 0.05 \)
- \( t = 2 \) years

\[
\text{SI} = P \times r \times t = 150 \times 0.05 \times 2 = 15
\]

\[
\text{Ending Balance} = P + \text{SI} = 150 + 15 = 165
\]

Answer: $165

---

3. $1,400 at 3% for 4 years

- \( P = 1,400 \)
- \( r = 3\% = 0.03 \)
- \( t = 4 \) years

\[
\text{SI} = P \times r \times t = 1,400 \times 0.03 \times 4 = 168
\]

\[
\text{Ending Balance} = P + \text{SI} = 1,400 + 168 = 1,568
\]

Answer: $1,568

---

4. $450 at 9% for 8 years

- \( P = 450 \)
- \( r = 9\% = 0.09 \)
- \( t = 8 \) years

\[
\text{SI} = P \times r \times t = 450 \times 0.09 \times 8 = 324
\]

\[
\text{Ending Balance} = P + \text{SI} = 450 + 324 = 774
\]

Answer: $774

---

5. $2,400 at 5% for 2 years

- \( P = 2,400 \)
- \( r = 5\% = 0.05 \)
- \( t = 2 \) years

\[
\text{SI} = P \times r \times t = 2,400 \times 0.05 \times 2 = 240
\]

\[
\text{Ending Balance} = P + \text{SI} = 2,400 + 240 = 2,640
\]

Answer: $2,640

---

6. $600 at 4.5% for 5 months

- \( P = 600 \)
- \( r = 4.5\% = 0.045 \)
- \( t = 5 \) months = \( \frac{5}{12} \) years

\[
\text{SI} = P \times r \times t = 600 \times 0.045 \times \frac{5}{12} = 11.25
\]

\[
\text{Ending Balance} = P + \text{SI} = 600 + 11.25 = 611.25
\]

Answer: $611.25

---

7. $15,600 at 5.5% for 6 years

- \( P = 15,600 \)
- \( r = 5.5\% = 0.055 \)
- \( t = 6 \) years

\[
\text{SI} = P \times r \times t = 15,600 \times 0.055 \times 6 = 5,148
\]

\[
\text{Ending Balance} = P + \text{SI} = 15,600 + 5,148 = 20,748
\]

Answer: $20,748

---

8. $1,300 at 4% for 3 years

- \( P = 1,300 \)
- \( r = 4\% = 0.04 \)
- \( t = 3 \) years

\[
\text{SI} = P \times r \times t = 1,300 \times 0.04 \times 3 = 156
\]

\[
\text{Ending Balance} = P + \text{SI} = 1,300 + 156 = 1,456
\]

Answer: $1,456

---

9. $750 at 5.5% for 5 years

- \( P = 750 \)
- \( r = 5.5\% = 0.055 \)
- \( t = 5 \) years

\[
\text{SI} = P \times r \times t = 750 \times 0.055 \times 5 = 206.25
\]

\[
\text{Ending Balance} = P + \text{SI} = 750 + 206.25 = 956.25
\]

Answer: $956.25

---

10. $850 at 2.2% for 11 months

- \( P = 850 \)
- \( r = 2.2\% = 0.022 \)
- \( t = 11 \) months = \( \frac{11}{12} \) years

\[
\text{SI} = P \times r \times t = 850 \times 0.022 \times \frac{11}{12} = 17.0833
\]

\[
\text{Ending Balance} = P + \text{SI} = 850 + 17.0833 = 867.08
\]

Answer: $867.08

---

11. $20,600 at 5.5% for 4 years

- \( P = 20,600 \)
- \( r = 5.5\% = 0.055 \)
- \( t = 4 \) years

\[
\text{SI} = P \times r \times t = 20,600 \times 0.055 \times 4 = 4,532
\]

\[
\text{Ending Balance} = P + \text{SI} = 20,600 + 4,532 = 25,132
\]

Answer: $25,132

---

12. $100 at 2% for 9 months

- \( P = 100 \)
- \( r = 2\% = 0.02 \)
- \( t = 9 \) months = \( \frac{9}{12} = 0.75 \) years

\[
\text{SI} = P \times r \times t = 100 \times 0.02 \times 0.75 = 1.5
\]

\[
\text{Ending Balance} = P + \text{SI} = 100 + 1.5 = 101.5
\]

Answer: $101.50

---

13. $4,000 at 4% for 3 years

- \( P = 4,000 \)
- \( r = 4\% = 0.04 \)
- \( t = 3 \) years

\[
\text{SI} = P \times r \times t = 4,000 \times 0.04 \times 3 = 480
\]

\[
\text{Ending Balance} = P + \text{SI} = 4,000 + 480 = 4,480
\]

Answer: $4,480

---

14. $7,400 at 2.2% for 9 months

- \( P = 7,400 \)
- \( r = 2.2\% = 0.022 \)
- \( t = 9 \) months = \( \frac{9}{12} = 0.75 \) years

\[
\text{SI} = P \times r \times t = 7,400 \times 0.022 \times 0.75 = 125.7
\]

\[
\text{Ending Balance} = P + \text{SI} = 7,400 + 125.7 = 7,525.70
\]

Answer: $7,525.70

---

15. $1,900 at 6% for 3 years

- \( P = 1,900 \)
- \( r = 6\% = 0.06 \)
- \( t = 3 \) years

\[
\text{SI} = P \times r \times t = 1,900 \times 0.06 \times 3 = 342
\]

\[
\text{Ending Balance} = P + \text{SI} = 1,900 + 342 = 2,242
\]

Answer: $2,242

---

16. $7,300 at 5.2% for 3 months

- \( P = 7,300 \)
- \( r = 5.2\% = 0.052 \)
- \( t = 3 \) months = \( \frac{3}{12} = 0.25 \) years

\[
\text{SI} = P \times r \times t = 7,300 \times 0.052 \times 0.25 = 94.9
\]

\[
\text{Ending Balance} = P + \text{SI} = 7,300 + 94.9 = 7,394.90
\]

Answer: $7,394.90

---

17. $210 at 5.9% for 3 years

- \( P = 210 \)
- \( r = 5.9\% = 0.059 \)
- \( t = 3 \) years

\[
\text{SI} = P \times r \times t = 210 \times 0.059 \times 3 = 38.37
\]

\[
\text{Ending Balance} = P + \text{SI} = 210 + 38.37 = 248.37
\]

Answer: $248.37

---

18. $35,100 at 3.6% for 3 months

- \( P = 35,100 \)
- \( r = 3.6\% = 0.036 \)
- \( t = 3 \) months = \( \frac{3}{12} = 0.25 \) years

\[
\text{SI} = P \times r \times t = 35,100 \times 0.036 \times 0.25 = 315.9
\]

\[
\text{Ending Balance} = P + \text{SI} = 35,100 + 315.9 = 35,415.90
\]

Answer: $35,415.90

---

Final Answers:

\[
\boxed{
\begin{array}{ll}
1. & \$39,312 \\
2. & \$165 \\
3. & \$1,568 \\
4. & \$774 \\
5. & \$2,640 \\
6. & \$611.25 \\
7. & \$20,748 \\
8. & \$1,456 \\
9. & \$956.25 \\
10. & \$867.08 \\
11. & \$25,132 \\
12. & \$101.50 \\
13. & \$4,480 \\
14. & \$7,525.70 \\
15. & \$2,242 \\
16. & \$7,394.90 \\
17. & \$248.37 \\
18. & \$35,415.90 \\
\end{array}
}
\]