Exercise 32 Page 270

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

Principal	Annual Interest Rate	Time	Simple Interest
$12 000	4.25 %	5 years	$2550
$ 8500	6.5 %	18 months	$828.75
$15 500	8.75 %		$5425.00

We want to calculate the time. 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 is 15 500 dollars and the simple interest I is 5425.00 dollars. We also know that the interest rate of 8.75 % can be written as 0.0875. Now, we can substitute these values into the formula.

I=Prt

SubstituteValues

Substitute values

5425.00= 15 500( 0.0875)t

Multiply

Multiply

5425.00=1356.25t

DivEqn

.LHS /1356.25.=.RHS /1356.25.

5425.00/1356.25=1356.25t/1356.25

▼

Solve for t

WriteAsFrac

Write as a fraction

5425.00/135 625100=1356.25t/1356.25

ReduceFrac

a/b=.a /25./.b /25.

5425.00/54254=1356.25t/1356.25

DivByFracSL

.a /b/c.=a* c/b

5425.00* 4/5425=1356.25t/1356.25

MovePartNumRight

a* b/c=a/c* b

5425.00/5425* 4=1356.25/1356.25* t

QuotOne

a/a=1

1* 4=1* t

IdPropMult

Identity Property of Multiplication

4=t

RearrangeEqn

Rearrange equation

t=4

The time t is equal to 4 years. We can add this information to the table.

Principal	Annual Interest Rate	Time	Simple Interest
$12 000	4.25 %	5 years	$2550
$ 8500	6.5 %	18 months	$828.75
$15 500	8.75 %	4 years	$5425.00