Question 1172615
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Here is a quick and easy way to solve "mixture" problems like this, if a formal algebraic solution is not required.<br>
(1) $2100 interest on an investment of $30,000 is a return of 7%.
(2) 7% is 2/3 of the way from 5% to 8%. (view the three percentages on a number line, if it helps....)
(3) Therefore, 2/3 of the total investment was at the higher rate.<br>
ANSWER: 2/3 of $30,000, or $20,000, was invested at 8%; the other $10,000 at 5%.<br>
CHECK: .08(20,000)+.05(10,000) = 1600+500 = 2100<br>