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Interest = Principal x Rate x Time - Printable Mathematics Worksheets - Wayground

Interest = Principal x Rate x Time

20 questions

8th - 9th Grade

Mathematics

Interest = Principal × Rate × Time is a Grade 8–9 mathematics worksheet on applying the simple-interest formula to real-world word problems. Across 20 multiple-choice questions, students calculate interest, solve for the annual interest rate, determine how long money was borrowed or invested, and convert time from months to years. Scenarios include loans, lending, savings deposits, and a certificate of deposit, with some problems requiring students to find interest from a final repayment amount. This worksheet helps students connect the variables in the simple-interest formula to financial situations and select the correct solution from plausible answer choices. It is useful for guided practice, independent review, or checking whether students can identify the unknown quantity before calculating. The free printable worksheet includes a complete answer key for efficient checking and feedback.

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Interest = Principal x Rate x Time

Total questions: 20

Name
Class
Date
1.
You lend $240 to your friend.  He pays you back $270.  What interest rate did you charge your friend?
a)
88%
b)
20%
c)
12.5%
d)
10%
2.
Anna invested $2,500 at an annual rate of 5%.  How long will it take until Anna earns $1,125 in interest?
a)
5 years
b)
8 years
c)
10 years
d)
9 years
3.

Dan borrowed $2,000 for 6 months at 12% annual simple interest rate. How much interest is that?

a)

$120

b)

$144

c)

$1,200

d)

$1,440

4.

Principal = $500

Interest earned in 4 years = $60.

Find the interest rate.

a)

1%

b)

2%

c)

3%

d)

4%

5.

Jenna borrowed $5,000 for 3 years and had to pay $1,350 simple interest at the end of that time. What rate of interest did she pay?

a)

6%

b)

6%

c)

8%

d)

9%

6.

Sam borrowed $4,500 for 2 years and had to pay $630 simple interest at the end of that time. What rate of interest did he pay?

a)

6%

b)

7%

c)

8%

d)

9%

7.

If you are calculating the simple interest and you are given the time in months. How can you find the time in years?

a)

divide 12 by the months

b)

divide the months by 12

c)

multiply 12 times the months

d)

change the months to a decimal

8.

Principal = $1500

Interest earned = $60 per year

Find the interest rate.

a)

40%

b)

4%

c)

0.4%

d)

8%

9.

Principal = $500

Interest earned in 4 years = $60.

Find the interest rate.

a)

1%

b)

2%

c)

3%

d)

4%

10.

Jerry borrowed $4,000 for 5 years at 6% simple interest rate. How much interest is that?

a)

$800

b)

$1,000

c)

$1,200

d)

$1,500

11.

Sam borrowed $4,500 for 2 years and had to pay $630 simple interest at the end of that time. What rate of interest did he pay?

a)

6%

b)

7%

c)

8%

d)

9%

12.

If Chloe deposits $2,000 at USA Savings Bank, at the end of 2 years you will have received $240 in simple interest. What is the interest rate at USA Savings Bank?

a)

6%

b)

8%

c)

12%

d)

simple 24%

13.

Chloe borrowed $3,600 from USA Savings Bank for 18 months, and at the end of the 18 months she will repay $4,059 to the bank. What is the interest rate for this loan?

a)

8.5%

b)

9.5%

c)

12.5%

d)

2%

14.

Lloyd deposited $1,200 in a certificate of deposit (CD) at a yearly interest rate of 5.5%. He earned $198 in simple interest. How long was the CD for?

a)

2 years

b)

3 years

c)

5 years

d)

1 year

15.

Joanna borrowed $500 at an annual interest rate of 8%. At the end of the loan period, she had to pay back $530. How long was the loan for?

a)

9 months

b)

3 months

c)

6 months

d)

12 months

16.

Leroy borrowed $1500 at an annual simple interest rate of 12%. He paid $270 in interest. For what time period did Leroy borrow the money?

a)

8 years

b)

0.015 years

c)

1 1/2 years

d)

18 years

17.

What is 7.25% converted to a decimal?

a)

.725

b)

0.725

c)

0.0725

d)

7.25

18.

Craig borrows $1200 from a bank with 8% simple interest per year. Which amount represents what he will have to pay back in 2 years?

a)

$150

b)

$192

c)

$1350

d)

$1392

19.

The rate is given as a percent (%). Before using it in the simple interest formula, you must first convert it to a______.

a)

fraction

b)

decimal

c)

ratio

d)

dollar amount

20.

Mr. Peterson paid $1,020 in interest for a loan, which was given to him at a rate of 5% for 3 years. How much money did he borrow originally?

a)

$5,400

b)

$6,800

c)

$3,240

d)

$14,620

Answer Key

Interest = Principal x Rate x Time

Total questions: 20

1.
c) 12.5%
2.
d) 9 years
3.
a)

$120

4.
c)

3%

5.
d)

9%

6.
b)

7%

7.
b)

divide the months by 12

8.
b)

4%

9.
c)

3%

10.
c)

$1,200

11.
b)

7%

12.
a)

6%

13.
a)

8.5%

14.
a)

2 years

15.
a)

9 months

16.
c)

1 1/2 years

17.
c)

0.0725

18.
d)

$1392

19.
b)

decimal

20.
b)

$6,800

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FAQs

What does the Interest = Principal × Rate × Time worksheet cover?

This Grade 8–9 worksheet contains 20 multiple-choice word problems that apply the simple-interest formula to loans, investments, bank deposits, and a certificate of deposit. Students solve for interest, annual rate, or time, including problems that require converting months to years or finding interest from a final repayment amount.

How can I use this worksheet to teach solving simple-interest word problems?

First model how to identify the principal, rate, time, and interest in one of the worksheet’s loan or deposit scenarios before substituting values into the formula. Then have students explain whether the unknown is interest, rate, or time and discuss why a time stated in months must be divided by 12 to express it in years. Use the multiple-choice options to analyze why common calculations, such as treating the full repayment as interest, are incorrect.

What mistakes should I watch for when students complete this simple-interest worksheet?

Watch for students using the total repayment instead of subtracting the principal to find the interest, especially in the loan questions that give both amounts. Students may also use months as whole years rather than dividing by 12, or read a decimal rate such as 0.05 as 5 without converting it to a percent. When solving for rate or time, check that students rearrange the simple-interest relationship rather than multiplying all four given values.

How do I assign and grade this simple-interest worksheet?

The worksheet is available as a printable PDF and as a digital quiz on Wayground, and it includes a complete answer key for all 20 multiple-choice questions. Printable submissions can be graded by scanning student work with the Wayground for Teachers app. The PDF option can also support schools that are reducing screen time.

How can I differentiate this simple-interest worksheet for my students?

Use the worksheet’s Advanced Settings to adjust font size and spacing so the numerical information in the financial word problems is easier to track. You can also enable a dyslexia-friendly font or translate the worksheet into another language, which may help students read the loan, deposit, and investment scenarios more independently.

Where can I find more free worksheets like this on Wayground?

Wayground offers a comprehensive collection of free printable worksheets and practice problems across subjects, with downloadable PDFs and answer keys to help students master essential skills and concepts. Browse more resources at https://wayground.com/en-us/worksheets.

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