Question 283771
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Kevin invested part of his 10,000 bonus in a certificate of deposit that paid 6% annual simple interest, 
and the remainder in a mutual fund that paid 11% annual simple interest. 
If his total interest for that year was $900, how much did Kevin invest in the mutual fund?
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        The solution in the post by @mananth is incorrect, leading to wrong answer.

        I came to bring a correct solution.



<pre>
Let x be the amount invested at 11%.
Then the amount invested at 6% is (10000-x).


Write the annual interest equation

    0.11x + 0.06*(10000-x) = 900.


Simplify and find x

    0.11x + 600 - 0.06x = 900,

    0.11x - 0.06x = 900 - 600,

          0.05x   =     300

              x   =     300/0.05 = 6000.



<U>ANSWER</U>.  Kevin invested  $6000 in the mutual fund.


<U>CHECK</U>.  The total annual interest was  0.11*6000 + 0.06*(10000-6000) = 900 dollars,

        which is precisely correct.
</pre>

Solved correctly.