I think you are correct actually.
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Answer:
She will have earned 6,008.74 JUST in interest after 72 months
Step-by-step explanation
72 months/12 months = 6 years
33% interest
Principal: $1,325
No additional $$
Plug it into compound interest formula and the total is $7,333.74
I subtracted the initial investment to see how much interest was earned.
Answer:
So the portion of the loan lent at 4% is 21000(0.5955) = $12,505.5
And the portion of the loan lent at 15% is 21000(0.4045) = $8494.5
Step-by-step explanation:
This problem can be solved in several ways. The way I like is as follows.
Ask yourself at what interest would $ 21,000 yield and interest of $ 2,215 in one year ? The equation to solve is:
21000(P) = 2215
P = 0.1055 or 10.55 %
This number is a weighed average of the 4% yield and the 15% yield so the next equation to solve is
10.55 = 4(1 – X) + 15X
Where X is the proportion of the loan given at the indicated interest. So
10.55 = 4 – 4X + 15X
6.55 = 11X
X = 0.5955
1-X = 0.4045
So the portion of the loan lent at 4% is 21000(0.5955) = $12,505.5
And the portion of the loan lent at 15% is 21000(0.4045) = $8494.5