Question 1160600: Oboe a recent retiree, requires Ghc 6000 per year in extra income. She has Ghc 50000 to invest and can invest in B-rated bonds paying 15% per year or in a certificate of deposit (CD) paying 7% per year. How much money should Oboe invest in each to realize exactly Ghc 6000 in interest per year?
Found 2 solutions by ikleyn, greenestamps:
Answer by ikleyn(52781)   (Show Source):
You can put this solution on YOUR website! .
0.15*B + 0.07*(50000-B) = 6000
B =  = 31250.
ANSWER. 31250 invested at 15% and the rest, 50000-31250 = 18750 invested at 7%.
CHECK. 0.15*31250 + 0.07*18750 = 6000. ! Precisely correct !
Solved.
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It is a standard and typical problem on investments.
If you need more details, or if you want to see other similar problems solved by different methods, look into the lesson
- Using systems of equations to solve problems on investment
in this site.
You will find there different approaches (using one equation or a system of two equations in two unknowns), as well as
different methods of solution to the equations (Substitution, Elimination).
Also, you have this free of charge online textbook in ALGEBRA-I in this site
- ALGEBRA-I - YOUR ONLINE TEXTBOOK.
The referred lesson is the part of this online textbook under the topic "Systems of two linear equations in two unknowns".
Save the link to this online textbook together with its description
Free of charge online textbook in ALGEBRA-I
https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson
to your archive and use it when it is needed.
Answer by greenestamps(13200)  (Show Source):
You can put this solution on YOUR website!
Here is a quick and easy way to solve a mixture problem like this without formal algebra.
(1) Determine the average percent return on the investment.
 = 12%
(2) Determine where that average percentage lies between the two individual percentages.
From 7% to 15% is a difference of 8%; from 7% to 12% is a difference of 5%.
12% is 5/8 of the way from 7% to 15%.
That means 5/8 of the total should be invested at the higher rate.
ANSWER: 5/8 of $50,000, or $31,250, at 15%; the rest, $18,750, at 7%.
CHECK: 
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