SOLUTION: An investment of $4500 is made at an interest rate of 8% for one year. How much money must be invested at a rate 5% so that the total interest earned is 6% of the total investment?
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-> SOLUTION: An investment of $4500 is made at an interest rate of 8% for one year. How much money must be invested at a rate 5% so that the total interest earned is 6% of the total investment?
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Question 1128896: An investment of $4500 is made at an interest rate of 8% for one year. How much money must be invested at a rate 5% so that the total interest earned is 6% of the total investment? Answer by greenestamps(13200) (Show Source):
8% of $4500, plus 5% of an unknown amount x, equals 6% of the total, $4500+x:
That equation is relatively easy to solve, although the decimals might make it take some time.
Here is a MUCH easier way to solve the problem (assuming a formal algebraic solution is not required).
(1) The overall average of 6% is "twice as close" to 5% as it is to 8%.
(2) Therefore, twice as much must be invested at 5% as at 8%.
(3) Since $4500 is invested at 8%, the amount required to be invested at 5% is 2*$4500 = $9000.
