SOLUTION: PLEASE HELP! I want to get better at solving this kind of problem for my math class. Sarah invested some money in an account earning 10.2% simple interest and three times that a

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Question 1140929: PLEASE HELP! I want to get better at solving this kind of problem for my math class.
Sarah invested some money in an account earning 10.2% simple interest and three times that amount in an account earning 12% simple interest. She earned $462 in interest after one year. How much does Sarah! invest in each account?

Answer by ikleyn(52794) About Me  (Show Source):
You can put this solution on YOUR website!
.
Let x be an amount invested at 10.2%.


Then the amount invested at 12% is (3x) dollars, according to the condition.


The interest from the 10.2% account is 0.102*x  dollars.

The interest from the 12%   account is 0.12*(3x)   dollars.



Your equation is


    interest + interest      = total interest,   or


    0.102*x  + 0.12*(3x)     = 462   dollars.


From the equation, express x and calculate the answer


    x = 462%2F%280.102%2B3%2A0.12%29 = 1000 dollars.


Answer.  The amount at 10.2% is $1000;  the amount at 12% is 3 times it, i.e. = $3000.


Check.   0.102*1000 + 0.12*3000 = 462 dollars.   ! Correct !

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It is a typical and standard problem on investment.

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.