Question 141980
What if the interest earned by $8000 invested at a certain rate is $500 less than $12000 would earn at a rate 1% lower, at what rate is $8000 invested?
:
Let x = rate (in decimals) that $8000 is invested
then
(x-.01) = rate that $12000 is invested
:
A simple equation:
int at 12k = int at 8k + 500
:
12000(x-.01) = 8000x + 500
:
12000x - 120 = 8000x + 500
:
12000x - 8000x = 500 + 120
:
4000x = 620
x = {{{620/4000}}}
x = .155 which is 15.5% interest rate of the $8000
:
Check solution by finding the interest of each amt: (12k int = 14.5%)
.145 * 12000 = 1740
.155 *  8000 = 1240
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the difference: 500