Question 1109355
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The algebraic solution provided by the other tutor is of course fine; it is the standard method for solving "mixture" problems.<br>
But try this much faster method and see if you like it....<br>
(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%.<br>
Answer: 3/5 of $10,000, or $6000, at 8%; the rest, $4000, at 6%.