SOLUTION: Phyllis invested 64000 dollars, a portion earning a simple interest rate of 4 percent per year and the rest earning a rate of 7 percent per year. After one year the total interest
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Question 858600: Phyllis invested 64000 dollars, a portion earning a simple interest rate of 4 percent per year and the rest earning a rate of 7 percent per year. After one year the total interest earned on these investments was 3730 dollars. How much money did she invest 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 7.00% per annum ------------ Amount invested = y
67000
Interest----- 3730.00
Part I 4.00% per annum ---x
Part II 7.00% per annum ---y
Total investment
x + 1 y= 67000 -------------1
Interest on both investments
4.00% x + 7.00% y= 3730
Multiply by 100
4 x + 7 y= 373000.00 --------2
Multiply (1) by -4
we get
-4 x -4 y= -268000.00
Add this to (2)
0 x 3 y= 105000
divide by 3
y = 35000
Part I 4.00% $ 32000
Part II 7.00% $ 35000
CHECK
32000 --------- 4.00% ------- 1280.00
35000 ------------- 7.00% ------- 2450.00
Total -------------------- 3730.00
m.ananth@hotmail.ca
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