SOLUTION: An investor has $20,000 to invest. If part is invested at 8% and the rest at 12%, how much should be invested at each rate to yield 11% on the total amount?

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Question 769331: An investor has $20,000 to invest. If part is invested at 8% and the rest at 12%, how much should be invested at each rate to yield 11% on the total amount?


Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
Part I 8.00% per annum ------------- Amount invested =x
Part II 12.00% per annum----------- Amount invested = y
@11% interest on 20,000 will be $2,200
Interest----- 2200.00

Part I 8.00% per annum ---x
Part II 12.00% per annum ---y
Total investment
x + 1 y= 20000 -------------1
Interest on both investments
8.00% x + 12.00% y= 2200
Multiply by 100
8 x + 12 y= 220000.00 --------2
Multiply (1) by -8
we get
-8 x -8 y= -160000.00
Add this to (2)
0 x 4 y= 60000
divide by 4
y = 15000
Part I 8.00% $ 5000
Part II 12.00% $ 15000