Big Ideas Math: Modeling Real Life, Grade 7
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Big Ideas Math: Modeling Real Life, Grade 7 View details
6. Simple Interest
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Exercise 30 Page 270

Use the simple interest formula to find the interest.

$ 2550

Practice makes perfect

Let's start by looking at the first row of the given table!

Principal Annual Interest Rate Time Simple Interest
$12 000 4.25 % 5 years
We want to calculate the simple interest. We can do so using the simple interest formula that tells us that simple interest I is the product of the principal P, annual interest rate (in decimal form) r, and time (in years) t. I=Prt Here, the principal P is 12 000 dollars and the time t is 5 years. We also know that the interest rate of 4.25 % can be written as 0.0425. Now, we can substitute these values into the formula.
I=Prt
I= 12 000( 0.0425)( 5)
I=2550
The simple interest is $ 2550. We can use this information to complete the table.
Principal Annual Interest Rate Time Simple Interest
$12 000 4.25 % 5 years $ 2550