Question 1169392
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A quick and easy non-algebraic method for solving this kind of problem....<br>
(1) All $15,000 invested at 4% would yield $600 interest; all at 5% would yield $750 interest.
(2) The actual interest, $690, is 90/150 = 3/5 of the way from $600 to $750. (Picture the 3 numbers on a number line if it helps....)
(3) Therefore, 3/5 of the total was invested at the higher rate.<br>
ANSWER: 3/5 of the $15,000, or $9000, at 5%; the other $6000 at 4%.<br>
CHECK: .05(9000)+.04(6000) = 450+240=690<br>