SOLUTION: Melinda invested twice as much money in an account paying 5% simple interest as she did in an account paying 3.5% simple interest. If her total interest at the end of 1 yr is $30

Question 1137096: Melinda invested twice as much money in an
account paying 5% simple interest as she did in an account paying 3.5% simple interest. If her total interest at the end of 1 yr is $303.75, find the amount she invested in the 5% account.
Answer by ikleyn(52777) (Show Source): You can put this solution on YOUR website!
.

Let x be an amount invested at 5%, the unknown value under the question.

Then the amount invested at 3.5% is the 0.5x dollars, according to the condition.



Your basic equation is THIS:


interest + interest     = total interest


0.05*x   + 0.035*(0.5x) = 303.75.


0.05x    + 0.0175       = 303.75


0.0675x = 303.75   ====>  x =  = 4500.


Answer.  $4500 was invested at 5%  and half of that, $2250 dollars was invested at 3.5%.


Check.   0.05*4500 + 0.035*2250 =  303.75 dollars.   ! Precisely correct !

Solved.

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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.

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