SOLUTION: maggie won 10,000 in a baking contest and decided to invest her winning in stocks and bonds, where stocks yielded 8% and yielded 6% annual interest. if the total interest she earn

Question 1109355: maggie won 10,000 in a baking contest and decided to invest her winning in stocks and bonds, where stocks yielded 8% and yielded 6% annual interest. if the total interest she earned at the end of one year was $720, how much did she invest in each?
thanks!
Found 2 solutions by josmiceli, greenestamps:
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Use simple interest formula,
(1)
(2)
------------------------------------------
(1)
(2)
(2)
-------------------------------
Plug (1) into (2)
(2)
(2)
(2)

--------------------------------
Maggie invested $6,000 in stocks
and $4,000 in bonds
--------------------------------
check:
(2)
(2)
(2)
and
(1)
(1)
(1)
and
as it should

Answer by greenestamps(13215) (Show Source): You can put this solution on YOUR website!

The algebraic solution provided by the other tutor is of course fine; it is the standard method for solving "mixture" problems.

But try this much faster method and see if you like it....

(1) The $720 interest on the $10,000 investment represents a return of 7.2%.
(2) 7.2% is (1.2/2) = 3/5 of the way from 6% to 8%.
(3) So 3/5 of the money was invested at 8%.

Answer: 3/5 of $10,000, or $6000, at 8%; the rest, $4000, at 6%.
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