math
posted by jota .
if $9,000 is to be invested, part at 13% and the rest at 8% simple interest , how much should be invested at each rate so that the total annual return will be the same as $9,000 invested at 9% set up as a system of linear equation

math 
MathMate
It's a linear partition problem, since both investments are paid simple interest.
Amount invested at 8%
=$9000*(139)/(138)
=$7200
Amount invested at 13%
=$9000*(98)/(138)
=$1800
Alternatively, using algebra,
Let x=amount invested at 8%,
Then (9000x)=amount invested at 13%
and the interest obtained should be the same as $9000 invested at 9%:
x*(8/100)+(9000x)*(13/100)=9000*(9/100)
Isolate x,
x((138)/100)=9000(139)/100
x=9000*(139)/(138)=7200 as before.
Respond to this Question
Similar Questions

Math
An investment advisor invested a total of $12,000, part at 2.5% annual simple interest and part at 4% annual simple interest. The amount of interest earned for 1 year was $426. How much was invested at the 2.5% rate and how much was … 
algebra
two investments were made totaling $15,000. for a certain year these investments yielded $1432 in simple interest. part of the $15,000 was invested at 9% and part at 10%. find the amount invested at each rate. a total of $1150 was … 
Math
A total of $11,000 was invested. Part of the $11,000 was invested at 4% and the rest invested at 7%. If the investments earn $680 per year, how much was invested at each rate? 
Algebra
I invested $42,000 in three funds paying 5%, 7%, and 9% simple interest. The total annual interest from these investments was $2,600. The amount of money invested at 5% was $200 less than the amount invested at 7% and 9% combined. … 
algebra
Larry Mitchel invested part of his $32,000 advance at 7% annual simple interest and the rest at 6% annual simple interest. If this total yearly interest from both accounts was $2,050, find the amount invested at each. The amount invested … 
Algebra
The Smiths invested $14,000, part at 3% simple interest and the rest at 4% simple interest for a period of one year. if the total interest earned was $460, how much was invested at each rate? 
Math
An investment of $3,000 is made at an annual simple interest of 5%. How much additional monery must be invested at an annual simple interest rate of 8% so that the total annual interest earned is 7.5 of te original amount that you … 
simple interest
A total of $12,000 is invested into two simple interest accounts. On one account the annual simple interest rate is 12%, while on the second account the annual interest rate is 18%. How much should be invested at 12% so that the interest … 
math
An investment of $3,000 is made at an annual simple interest of 5%. How much additional money must be invested at an annual simple interest rate of 8%, so that the total annual interest earned is 7.5 of the original amount that you … 
Math
Larry Mitchell invested part of his $27,000 advance at 5% annual simple interest and the rest at 2% annual simple interest. If his total yearly interest from both accounts was $720â€‹, find the amount invested at each rate