SOLUTION: Sergio invests part of his 90,000 at 4% and the rest at 3%. How much is invested at each rate if he makes a total income of 3,100 annually? --HELP ME PLEASE I CANT DO IT BY MYSE

Question 723850: Sergio invests part of his 90,000 at 4% and the rest at 3%. How much is invested at each rate if he makes a total income of 3,100 annually?
--HELP ME PLEASE I CANT DO IT BY MYSELF :(
Found 2 solutions by lynnlo, mananth:
Answer by lynnlo(4176) (Show Source): You can put this solution on YOUR website!
4%=====================1 yr. value==========$46,833.39
total interest=========================$1,833.39
3%=====================1 yr. value==========$46,368.71
total interest=========================$1,368.71
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
Part I 3.00% per annum ------------- Amount invested =x
Part II 4.00% per annum ------------ Amount invested = y =
90000
Interest----- 3100

Part I 3.00% per annum ---x
Part II 4.00% per annum ---y
Total investment
x + 1 y= 90000 -------------1
Interest on both investments
3.00% x + 4.00% y= 3100
Multiply by 100
3 x + 4 y= 310000.00 --------2
Multiply (1) by -3
we get
-3 x -3 y= -270000.00
Add this to (2)
0 x 1 y= 40000
divide by 1
y = 40000
Part I 3.00% $ 50000
Part II 4.00% $ 40000

CHECK
50000 --------- 3.00% ------- 1500.00
40000 ------------- 4.00% ------- 1600.00
Total -------------------- 3100.00

m.ananth@hotmail.ca

RELATED QUESTIONS
Sergio invests part of his 90,000 PESOS at 4% and the rest at 3%. How much money is... (answered by mananth)
A man invests part of $6,000 at 4% interest and the rest at 3% interest. His total annual (answered by checkley77)
A man invested P140,000. Part of his capital was invested at 11% and the rest at 9%. If... (answered by Theo,greenestamps)
A man has $5000 to invest. He invests part of it at 4 per cent, and the rest at 3 per... (answered by richwmiller)
Joe invests $6000, part at 5% interest and the rest at 7%. If his annual interest income... (answered by mananth)
A man invests $1200, part at 5% and part at 4% per annum, and his total income is $55.50. (answered by mananth)
Solve this problem by using a two order system. A man invests $5,200, part at 4% and... (answered by nerdybill)
A man invests $5,200, part at 4% and the balance at 3%. If his total income for the two... (answered by ReadingBoosters)
Willard invests a part of 50 000 pesos in a bank paying 12% interest annually and the... (answered by richwmiller)