SOLUTION: linda invested some money for one year in bonds that pay 8% simple interest and three times as much in preferred stock that earns 11% simple interest. if the total interest earned

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Question 1111897: linda invested some money for one year in bonds that pay 8% simple interest and three times as much in preferred stock that earns 11% simple interest. if the total interest earned from the two investments was $1640, how much was invested in the bonds?
Found 2 solutions by ikleyn, josmiceli:
Answer by ikleyn(52790) About Me  (Show Source):
You can put this solution on YOUR website!
.
The basic equation is

0.08*x + 0.11*(3x) = 1640  dollars.


Solve for x, which is an amount invested in bonds at 8%.

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To see many other similar solved problems on investment,  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 josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Use simple interest formula
+I+=+P%2Ar%2At+
Let +I+ = interest earned from 8% investment
+1640+-+I+ = interest earned from 11% investment
Let +P+ = amount invested at 8%
+3P+ = amount invested at 11%
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For 8% investment:
(1) +I+=+P%2A.08%2A1+
For 11% investment:
(2) +1640+-+I+=+3P%2A.11%2A1+
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(1) +I+=+.08P+
and
(2) +1640+-+I+=+.33P+
Plug (1) into (2)
(2) +1640+-+.08P+=+.33P+
(2) +.41P+=+1640+
(2) +P+=+4000+
and
+3P+=+12000+
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$4,000 was invested @ 8%
$12,000 was invested @ 11%