Question 1163997
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If a formal algebraic solution is not required, here is a quick and easy informal way of solving two part "mixture" problems like this.<br>
All $21,000 invested at 5% would yield $1050 interest; all at 6% would yield $1260 interest.<br>
The actual interest was $1180.<br>
Picture the three amounts on a number line: 1050, 1180, and 1260.  1180 is 13/21 of the way from 1050 to 1260.  (1050 to 1260 is a difference of 210; 1050 to 1180 is a difference of 120; 130/210 = 13/21.)<br>
That means 13/21 of the total was invested at the higher rate.<br>
ANSWER: 13/21 of $21,000, or $13,000, at 6%; the other $8000 at 5%.<br>
CHECK:
.06(13000)+.05(8000) = 780+400 = 1180<br>