# The amount invested at interest rate 4 1 2 % and interest rate 4%.

BuyFind

### Precalculus: Mathematics for Calcu...

6th Edition
Stewart + 5 others
Publisher: Cengage Learning
ISBN: 9780840068071
BuyFind

### Precalculus: Mathematics for Calcu...

6th Edition
Stewart + 5 others
Publisher: Cengage Learning
ISBN: 9780840068071

#### Solutions

Chapter 1.6, Problem 21E
To determine

Expert Solution

## Answer to Problem 21E

The amount invested at 412% rate is $9000 and amount invested at 4% rate is$3000.

### Explanation of Solution

Given:

Phyllis invested a portion of $12,000 at a rate of 412% and the remaining amount at rate of 4%. The interest earned after 1 year is$525.

Calculation:

Let the amount invested at 412% rate be x and the amount invested on 4% rate be 12,000x .

Tabulate the given information into the language of algebra.

 In words In Algebra Amount invested at 412% x Amount invested at 4% 12,000−x Interest earned at 412% 0.045x Interest earned at 4% 0.04(12000−x)

Model the equation for the above information.

Interestat412%+Interestat4%=Totalinterest0.045x+0.04(12,000x)=525

Simplify the above equation for x,

0.045x+4800.04x=5250.005x+480=5250.005x=45(Subtract480)x=9000

The amount invested at 4% rate is,

12000x=120009000=3000

Thus, the amount invested at 412% rate is $9000 and amount invested at 4% rate is$3000.

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