Expert: Richard J. Raridon - 11/2/2006

Question
I have looked everywhere for an example(s) involving investments with system of linear equations and have come up empty handed. I would be most appreciative with any help that I can get.
#1) A retired couple has $200,000 to invest to obtain annual income. They want some of it invested in safe certificates of deposit yielding 5%. The rest they want to invest in AA bonds yielding 10% per year. How much should they invest in each to realize exactly $17,000 per year?
#2) Lexie wants to have an income of $9000 per year from investments. To that end she is going to invest $90,000 in three different accounts. These accounts pay 7%, 10%, and 14% simple interest. If she wants to have $10,000 more in the account paying 7% simple interest than she has in the account paying 14% simple interest, how much should go into each account?
~Thank you sooo much, Terri

Answer
#1) let x = amt. invested at 5% and y = amt. at 10%
then x+y = 200000 and 0.05x +0.10y = 17000, solve for x and y.  
#2) let x = amt. invested at 7%, y = amt. at 10% and z + amt. at 14%.  
then x+y+z = 90000, 0.07x +0.10y +0.14z = 9000,
x = z +10000, solve for x,y, and z