6-6 Simple Interest
Course 2
Warm UpWarm Up
Problem of the DayProblem of the Day
Lesson PresentationLesson Presentation
Warm UpMultiply.
1. 800 0.04 3
2. 1,700 2 0.25
3. 900 0.05 4
4. 1,200 6 0.35
96
850
180
Course 2
6-6 Simple Interest
2,520
Problem of the DayWhich number does not belong in the group?
0.75 75%
Course 2
6-6 Simple Interest
34
68
751,000
751,000
= ;340
the others equal . 34
Learn to solve problems involving simple interest.
Course 2
6-6 Simple Interest
Vocabulary
interestsimple interestprincipal
Insert Lesson Title Here
Course 2
6-6 Simple Interest
Course 2
6-6 Simple Interest
When you keep money in a savings account, your money earns interest.
Interest is an amount that is collected or paid for the use of money. For example, the bank pays you interest to use your money to conduct its business.
Likewise, when you borrow money from the bank, the bank collects interest on its loan to you.
Course 2
6-6 Simple Interest
One type of interest, called simple interest, is money paid only on the principal.
The principal is the amount of money deposited or borrowed.
To solve problems involving simple interest, you can use the following formula.
I = P · r · t
Interest
Principal
Rate of interest per year(as a decimal)
Time in years that themoney earns interest
Find the missing value.
Additional Example 1A: Using the Simple Interest Formula
Course 2
6-6 Simple Interest
A. I = , P = $575, r = 8%, t = 3 years
I = P · r · t
I = 575 · 0.08 · 3
I = $138
The simple interest is $138.00.
Substitute. Use 0.08 for 8%.
Multiply.
Find the missing value.
Additional Example 1B: Using the Simple Interest Formula
Course 2
6-6 Simple Interest
B. I = $204, P = $1,700, r = , t = 6 years
I = P · r · t
204 = 1,700 · r · 6
204 = 10,200r
20410,200
= 10,200r10,200
0.02 = r
The interest rate is 2%
Substitute.
Multiply.
Divide by 10,200 to isolate the variable.
Find the missing value.
Try This: Example 1A
Course 2
6-6 Simple Interest
A. I = , P = $525, r = 7%, t = 2 years
I = P · r · t
I = 525 · 0.07 · 2
I = $73.50
The simple interest is $73.50.
Substitute. Use 0.07 for 7%.
Multiply.
Find the missing value.
Try This: Example 1B
Course 2
6-6 Simple Interest
B. I = $600, P = $2,000, r = , t = 3 years
I = P · r · t
600 = 2,000 · r · 3
600 = 6,000r
6006000
= 6,000r6,000
0.1 = r
The interest rate is 10%
Substitute.
Multiply.
Divide by 10,200 to isolate the variable.
Lesson Quiz
Find each missing value.
1. I =
2. I = $18, P = $150, r =
3. I = $640, P =
4. I = $120, P = $600, r = 5% t =
6%
$240
Insert Lesson Title Here
$2,000
4 years
Course 2
6-6 Simple Interest
, P = $800, r = 10%, t = 3 years
, t = 2 years
, r = 4%, t = 8 years
WP: Simple interest
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