Answer: she invested $10000 on the in b-rated bonds.
she invested $50000 in a cd deposit
Explanation:
Let x represent the amount invested in b-rated bonds paying 15% per year.
Let y represent the amount invested in a cd deposit paying 7% per year.
She has 60,000 to invest in b-rated bonds paying 15% per year or in a cd deposit paying 7% per year. This means that
x + y = 60000
The formula for determining simple interest is expressed as
I = PRT/100
Where
I represents interest on the investment.
P represents the principal or amount invested.
R represents interest rate
T represents the duration of the investment in years.
Considering the amount invested in b-rated bonds paying 15% per year.,
P = x
R = 15
T = 1 year
I = (x × 15 × 1)/100 = $0.15x
Considering the amount invested in a cd deposit paying 7% per year.,
P = y
R = 7
T = 1 year
I = (y × 7 × 1)/100 = $0.07y
In order to realize exactly 5,000 in interest per year, then
0.15x + 0.07y = 5000 - - - - - - 1
Substituting x = 60000 - y into equation 1, it becomes
0.15(60000 - y) + 0.07y = 5000
9000 - 0.15y + 0.07y = 5000
- 0.15y + 0.07y = 5000 - 9000
- 0.08y = - 4000
y = - 4000/- 0.08
y = 50000
x = 60000 - y = 60000 - 50000
x = $10000