SOLUTION: Judith invested $13,000 for 1year, part at 10% interest and part at 9% interest. If she earned a total of $1150 in interest, howyvh did she invest at each rate?

Question 585029: Judith invested $13,000 for 1year, part at 10% interest and part at 9% interest. If she earned a total of $1150 in interest, howyvh did she invest at each rate?
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
udith invested $13,000 for 1year, part at 10% interest and part at 9% interest.
If she earned a total of $1150 in interest, how much did she invest at each rate?
:
Let a = amt invested at 10%
Let b = amt invested at 9%
:
The total investment equation
a + b = 13000
b = (13000-a), use this form for substitution
:
The total interest equation
.10a + .09b = 1150
Replace b with (13000-a)
.10a + .09(13000-a) = 1150
.10a + 1170 - .09a = 1150
Right here we can see there is flaw in this problem
.10a - .09a = 1150 - 1170
.01a = -20, a negative here is not reasonable, check the source of the problem
:
Anyway, this method should be helpful to you. C
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