SOLUTION: A total of $5000 is invested at 3% and 5% annual interest. After 1 year, the total interest equals $210. How much money is invested at each interest rate?

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Question 1000227: A total of $5000 is invested at 3% and 5% annual interest. After 1 year, the total interest equals $210. How much money is invested at each interest rate?
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
Part I 3.00% per annum ------------- Amount invested =x
Part II 5.00% per annum ------------ Amount invested = y = 3 x
5000
Interest----- 210

Part I 3.00% per annum ---x *
Part II 5.00% per annum ---y
Total investment
x + 1 y= 5000 -------------1
Interest on both investments
3.00% x + 5.00% y= 210
Multiply by 100
3 x + 5 y= 21000.00 --------2
Multiply (1) by -3
we get
-3 x -3 y= -15000.00
Add this to (2)
0 x 2 y= 6000
divide by 2
y = 3000 -
Part I 3.00% $ 2000
Part II 5.00% $ 3000

CHECK
2000 --------- 3.00% ------- 60.00
3000 ------------- 5.00% ------- 150.00
Total -------------------- 210.00

m.ananth@hotmail.ca