 # Simple Interest 7th Grade Math.

## Presentation on theme: "Simple Interest 7th Grade Math."— Presentation transcript:

Vocabulary Interest Principal Simple Interest
Money paid or earned for the use of money Principal The amount of money borrowed or invested Simple Interest Money paid or earned only on the principal

Simple Interest Formula
I = Prt Annual Interest Rate (in decimal form) Simple Interest Principal Time (in years)

Finding Interest Earned
You put \$500 in a savings account. The account ears 3% simple interest per year. What is the interest earned after 3 years? I = Prt I = 500 · .03 · 3 I = 45 What is the balance after 3 years? = \$545

Check Yourself You put \$200 in a savings account. The account earns 2% simple interest annually. What is the interest earned after 5 years? What is the balance after 5 years?

Finding Annual Interest Rate
You put \$1000 in an account. The account earns \$100 simple interest in 4 years. What is the annual interest rate? I = Prt 100 = 1000 · r · 4 100 = 4000 · r r = becomes 2.5%

Check Yourself You put \$700 in an account. The account earns \$224 simple interest in 8 years. What is the annual interest rate?

Finding an Amount of Time
A bank offers an annual simple interest rate of 2.0% for balances between \$500 and \$5000. How long will does it take an account with a principal of \$800 to earn \$100 interest? I = Prt 100 = 800 · .02 · t 100 = 16 · t t = 6.25 or 6 years 3 months

Check Yourself A bank offers an annual simple interest rate of 1.5% for balances under \$500. How long does it take an account with a principal of \$400 to earn \$36 interest?

Finding Amount Paid on a Loan
You borrow \$600 to buy a violin. The simple interest rate is 15%. You pay off the loan after 5 years. How much do you pay for the loan? I = Prt I = 600 · .15 · 5 I = 450 (this is just interest) Principal + Interest = Total Paid = \$1050

Check Yourself You borrow \$300 to buy a guitar. The simple interest rate is 12%. You pay off the loan after 4 years. How much do you pay for the loan?