SOLUTION: A total of $3700 was invested, part of it at 6% interest and the remainder at 11%. If the total yearly interest amounted to $330, how much was invested at each rate?

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Question 779591: A total of $3700 was invested, part of it at 6% interest and the remainder at 11%. If the total yearly interest amounted to $330, how much was invested at each rate?
Found 2 solutions by mananth, josgarithmetic:
Answer by mananth(16949) About Me  (Show Source):
You can put this solution on YOUR website!
Part I 6.00% per annum ------------- Amount invested =x
Part II 11.00% per annum ------------ Amount invested = y
3700
Interest----- 330.00

Part I 6.00% per annum ---x
Part II 11.00% per annum ---y
Total investment
x + 1 y= 3700 -------------1
Interest on both investments
6.00% x + 11.00% y= 330
Multiply by 100
6 x + 11 y= 33000.00 --------2
Multiply (1) by -6
we get
-6 x -6 y= -22200.00
Add this to (2)
0 x 5 y= 10800
divide by 5
y = 2160 - x)
Part I 6.00% $ 1540
Part II 11.00% $ 2160

CHECK
1540 --------- 6.00% ------- 92.40
2160 ------------- 11.00% ------- 237.60
Total -------------------- 330.00

m.ananth@hotmail.ca

Answer by josgarithmetic(39790) About Me  (Show Source):
You can put this solution on YOUR website!
A total of $3700 was invested, part of it at 6% interest and the remainder at 11%.
If the total yearly interest amounted to $330, how much was invested at each rate?
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A total of $T was invested, part of it at c% interest and the remainder at g%.
If the total yearly interest amounted to $n, how much was invested at each rate?
(All values are as variables.)
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invested v at g% and therefore invested T-g at c%.
The amounts of earned interests were %28c%2F100%29%28T-v%29 and %28g%2F100%29v.
Their sum n, was given, so %28c%2F100%29%28T-v%29%2B%28g%2F100%29v=n.
Solve the equation for v.
c%28T-v%29%2Bgv=100n
cT-cv%2Bgv=100n
gv-cv=100n-cT
highlight%28v=%28100n-cT%29%2F%28g-c%29%29, for ALL such examples which fit this same exact format.