SOLUTION: The annual interest on a $9000 investment exceeds the interest earned on an $8000 investment by $103. The $9000 is invested at a 0.7% higher rate of interest than the $8000. What s

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Question 945216: The annual interest on a $9000 investment exceeds the interest earned on an $8000 investment by $103. The $9000 is invested at a 0.7% higher rate of interest than the $8000. What s the interest rate of each investment?

I've done simple interest question but I honesty have no idea what to do with this one.
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
The annual interest on a $9000 investment exceeds the interest earned on an $8000 investment by $103.
The $9000 is invested at a 0.7% higher rate of interest than the $8000.
What is the interest rate of each investment?
:
let r = interest rate on the $8000 investment, in decimal form
then
(r + .007) = interest rate on the $9000 investment in decimal form
:
9000(r+.007) - 8000r = 103
9000r + 63 - 8000r = 103
1000r = 103 - 63
1000r = 40
r = 40%2F1000
r = .04, which is 4% interest on the $8000
then, obviously:
4.7% is the interest rate on the $9000
:
:
Let see if this adds up, find the interest on each
.047(9000) = 423
.04(8000) = $320
-------------------
difference: $103