Calculating Interest

Calculating Interest Review

Remember two different interests.

Interest

Interest is the amount earned when savings or on debt owed.

There is simple interest: i =prt

There is compound interest: A = p(1+r)^t

Using Desmos For Interest.

1. Write down the simple or compound interest formula

2. Write down the variables you know.

3. Enter the formula and the variables you written down in desmos.

If Simple Interest: Use this decision tree chart.

Multiple Choice

What is the formula for simple interest?

• T = pri

• I = prt

• R = ipt

• P = irt

Multiple Choice

The "p" in I = prt stands for...

• portion

• pre-Algebra

• percent

• principal

Multiple Choice

Caiden earned $475 from mowing lawns last summer. He deposited this money in an account that pays a simple interest rate of 3.8%. What will be the amount of interest earned after 15 years?

• $3182.50

• $270.75

• $2707.50

• $745.75

Multiple Choice

Determine the simple interest earned:  p= $2000  r= 4.6%  t= 4 years

• $2370.00
• $348.00
• $2368.00
• $368.00

Multiple Choice

Emily’s parents put $1500 in her bank account for college tuition at a simple interest rate of 8.25%. What will be the balance after 18 years?

• $22,275

• $2227.50

• $12,375

• $3727.50

Multiple Choice

Olivia would like to buy some new furniture for her home. She decides to buy the furniture on credit with 9.5% simple interest. If she spent $7400 on furniture, how much will she have paid in total after 8 years?

• $5624

• $13,024

• $56,240

• $1302.40

If Simple Interest: Use this decision tree chart.

Multiple Choice

Mr. Flores opend an account with a deposit of $5000

• *The accound earned annual simple interest.

• * He did not make any additional depositis of withdrawals.

• *At the end of 4 years, the blaance of the account was $6500.

What is the annual interest rate on this account?

• 5.8%

• 7.5%

• 3.3%

• 1.9%

If compound Interest: Use this decision tree chart.

Multiple Choice

Your 3 year investment of $20,000 received 5.2% interest compounded annually.  What is your total return?

• $23,285.05
• $3,285.05
• $2,385
• $32,285

Multiple Choice

Find the compound interest:
Principal: $1735
Interest Rate: 0.8%
Time: 1 year

• $1,388
• $138.80
• $13.88
• None of the answers are correct.

Multiple Choice

Mr. Wilkins deposited $2500 in a new account at his bank.

• * The bank pays 6.5% interest compounded annually on this account.

• * Mr. Wilkins makes no additional deposits or withdrawals.

Which amount is closest to the balance of the account at the end of 2 years?

• $2,835.56

• $2,513.00

• $2,662.50

• $2,825.00