Answer:$12500 was invested into the account that pays 4.5% annual interest..
$2500 was invested into the the certificate of deposit that pays 1.8% annual interest..
Step-by-step explanation:
Let x represent the amount invested into the account that pays 4.5% annual interest.
Let y represent the amount invested into the certificate of deposit that pays 1.8% annual interest.
Sean has 15,000 to invest. She will put some of it into a fund that pays 4.5% annual interest and the rest in a certificate of deposit that pays 1.8% annual interest. This means that
x = y + 15000
The formula for simple interest is expressed as
I = PRT/100
Where
P represents the principal
R represents interest rate
T represents time in years
I = interest after t years
Considering the account earning 4.5% interest, the interest would be
I = (x × 4.5 × 1)/100 = 0.045x
Considering the account earning 11% interest, the interest would be
I = (x × 1.8 × 1)/100 = 0.018y
if she wants to earn 4.05% annual interest on the total amount, the amount would be
4.05/100 × 15000 = 607.5
Therefore,
0.045x + 0.018y = 607.5 - - - - - - - - - - -1
Substituting x = 15000 - y into equation 1, it becomes
0.045(15000 - y) + 0.018y = 607.5
675 - 0.045y + 0.018y = 607.5
- 0.045y + 0.018y = 607.5 - 675
- 0.027y = - 67.5
y = - 67.5/- 0.027
y = $2500
x = 15000 - y = 15000 - 2500
x = $12500
