Simple interest worksheet

Grade 7 math, Common Core 7.RP.A.3. 10 problems with an answer key and worked steps. Free to print, and you can make new problems any time.

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Simple interest

Grade 7 math, Common Core 7.RP.A.3

Use I = Prt to answer each question.

1.
Ravi borrows $1,600 at 3% simple interest a year for 5 years. What is the total paid back?
2.
$1,700 earns $102.00 in simple interest over 3 years. What is the yearly interest rate?
3.
$1,100 earns $176.00 in simple interest over 4 years. What is the yearly interest rate?
4.
$3,200 earns $640.00 in simple interest over 5 years. What is the yearly interest rate?
5.
$2,900 earns $870.00 in simple interest over 5 years. What is the yearly interest rate?
6.
Ethan borrows $2,000 at 6% simple interest a year for 4 years. What is the total paid back?
7.
Grace borrows $800 at 3% simple interest a year for 4 years. What is the total paid back?
8.
$5,000 earns $200.00 in simple interest over 2 years. What is the yearly interest rate?
9.
Mateo borrows $3,500 at 3% simple interest a year for 5 years. What is the total paid back?
10.
Sam puts $700 in a savings account that pays 3% simple interest a year. How much interest is earned in 4 years?

Answer key: Simple interest

Grade 7 math. Each answer has a few worked steps, to help check the method as well as the answer.

1. $1,840.00
I = 1,600 × 0.03 × 5 = 240Total: 1,600 + 240 = 1,840
2. 2%
r = I ÷ (Pt) = 102 ÷ (1,700 × 3) = 0.02
3. 4%
r = I ÷ (Pt) = 176 ÷ (1,100 × 4) = 0.04
4. 4%
r = I ÷ (Pt) = 640 ÷ (3,200 × 5) = 0.04
5. 6%
r = I ÷ (Pt) = 870 ÷ (2,900 × 5) = 0.06
6. $2,480.00
I = 2,000 × 0.06 × 4 = 480Total: 2,000 + 480 = 2,480
7. $896.00
I = 800 × 0.03 × 4 = 96Total: 800 + 96 = 896
8. 2%
r = I ÷ (Pt) = 200 ÷ (5,000 × 2) = 0.02
9. $4,025.00
I = 3,500 × 0.03 × 5 = 525Total: 3,500 + 525 = 4,025
10. $84.00
I = 700 × 0.03 × 4 = 84

The answer key prints on its own page. You’re welcome to print and copy these worksheets for your own kids or class.

About simple interest

Simple interest is money paid for borrowing or saving money. The formula is I = Prt: the principal P (the money you start with) times the yearly rate r (as a decimal) times the time t in years. Add the interest to the principal to get the total.

Worked example 1

Sam borrows $4,700 at 5% simple interest a year for 1 year. What is the total paid back?

Step 1.I = 4,700 × 0.05 × 1 = 235
Step 2.Total: 4,700 + 235 = 4,935

Answer: $4,935.00

Worked example 2

Diego borrows $2,200 at 6% simple interest a year for 3 years. What is the total paid back?

Step 1.I = 2,200 × 0.06 × 3 = 396
Step 2.Total: 2,200 + 396 = 2,596

Answer: $2,596.00

Worked example 3

Priya puts $4,300 in a savings account that pays 2% simple interest a year. How much interest is earned in 3 years?

Step 1.I = 4,300 × 0.02 × 3 = 258

Answer: $258.00

Watch out for

Change the rate to a decimal first: 4% is 0.04.
Time must be in years: 6 months is 0.5 years.
The question may ask for the interest or the total. The total is P + I.

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