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Simple Interest

• Principal: The money you deposit in a savings account
• Interest: The money the bank pays you based on the interest rate
• Simple interest: The interest paid only on the principal
• Simple Interest Formula: I = prt
• I = interest (\$)
• p = principal (4)
• r = interest rate per year
• t = time in years

Find the simple interest. P = \$300 Interest rate = 15% Time = 10 years

• I = Prt
I = interest
P = principal
r = interest rate per year
t = time in years
• 15% = .15
• I = (300)(.15)(10)

Find the simple interest. P = \$150 Interest rate = 30% Time = 5 years

• I = Prt
• I = interest
P = principal
r = interest rate per year
t = time in years
• 30% = .30
• I = (150)(.30)(5)

Find the simple interest earned over 15 years when the principal is \$600 and the interest rate is 10 percent.

• I = Prt
• I = interest
P = \$600
r = 10%
t = 15
• 10% = .10
• I = (600)(.10)(15)

Find the simple interest earned over 30 years when the principal is \$400 and the interest rate is 5 percent.

• I = Prt
• I = interest
P = \$400
r = 5%
t = 30
• 5% = .05
• I = (400)(.05)(30)

Samantha deposited \$120 into a savings account with an interest rate of 10 percent. Find how much simple interest she earned over 9 years.

• I = Prt
• I = interest
P = \$120
r = 10%
t = 9
• 10% = .10
• I = (120)(.10)(9)

John deposited \$250 into a savings account with an interest rate of 20 percent. Find how much simple interest she earned over 15 years.

• I = Prt
• I = interest
P = \$ 250
r = 20%
t = 15
• 20% = .20
• I = (250)(.20)(15)

David deposited \$600 into a savings account with an interest rate of 2 percent. Find how much simple interest she earned over 6 years.

• I = Prt
• I = interest
P = \$ 600
r = 2%
t = 6
• 2% = .02
• I = (600)(.02)(6)

If the simple interest earned in 10 years is \$250 and the interest rate is 5%, how much is the principal?

• I = Prt
• I = \$ 250
P = principal
r = 5%
t = 10
• 5% = .05
• 250 = (P)(.05)(10)
• 250 = 0.5P
• P = [250/0.5]

If the simple interest earned in 10 years is \$500 and the interest rate is 2%, how much is the principal?

• I = Prt
• I = \$ 500
P = principal
r = 2%
t = 10
• 2% = .02
• 500 = (P)(.02)(10)
• 500 = 0.2P
• P = [500/0.2]

If the simple interest earned in 1 years is \$120 and the interest rate is 2%, how much is the principal?

• I = Prt
• I = \$120
P = principal
r = 2%
t = 1
• 2% = .02
• 120 = (P)(.02)(1)
• 120 = 0.02P
• P = [120/0.02]

\$ 6000

*These practice questions are only helpful when you work on them offline on a piece of paper and then use the solution steps function to check your answer.