SOLUTION: A woman invested some money at 8% and some at 9% annual simple interest. The interest for 1 year on the combined investment of $10,000 was $830. How much was invested at each rate?
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Question 805514: A woman invested some money at 8% and some at 9% annual simple interest. The interest for 1 year on the combined investment of $10,000 was $830. How much was invested at each rate? Answer by mananth(16946) (Show Source):
You can put this solution on YOUR website! Part I 8.00% per annum ------------- Amount invested =x
Part II 9.00% per annum ------------ Amount invested = y
10000
Interest----- 830.00
Part I 8.00% per annum ---x
Part II 9.00% per annum ---y
Total investment
x + 1 y= 10000 -------------1
Interest on both investments
8.00% x + 9.00% y= 830
Multiply by 100
8 x + 9 y= 83000.00 --------2
Multiply (1) by -8
we get
-8 x -8 y= -80000.00
Add this to (2)
0 x 1 y= 3000
divide by 1
y = 3000 -
Part I 8.00% $ 7000
Part II 9.00% $ 3000
