SOLUTION: You invested $8000 between two accounts paying 4% and 9% annual interest respectively. If the total interest earned for the year was $570, how much was invested at each rate?

Question 889507: You invested $8000 between two accounts paying 4% and 9% annual interest respectively. If the total interest earned for the year was $570, how much was invested at each rate?

Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
Part I 4.00% per annum ------------- Amount invested =x
Part II 9.00% per annum ------------ Amount invested = y
8000
Interest----- 570.00

Part I 4.00% per annum ---x
Part II 9.00% per annum ---y
Total investment
x + 1 y= 8000 -------------1
Interest on both investments
4.00% x + 9.00% y= 570
Multiply by 100
4 x + 9 y= 57000.00 --------2
Multiply (1) by -4
we get
-4 x -4 y= -32000.00
Add this to (2)
0 x 5 y= 25000
divide by 5
y = 5000
Part I 4.00% $ 3000
Part II 9.00% $ 5000

CHECK
3000 --------- 4.00% ------- 120.00
5000 ------------- 9.00% ------- 450.00
Total -------------------- 570.00

m.ananth@hotmail.ca

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