Answer:
$3,000
Step-by-step explanation:
As the total amount of investment = $8,000
This was invested partially at 9% and partially at 8%, which after a year resulted into interest revenue of $690.
Therefore, let investment @ 9% be $x
Thus, $x
9% + ($8,000 - $x)
8% = $690
0.09x + $640 - 0.08x = $690
0.01x = $690 - $640 = $50
x = $50/0.01 = $5,000
Therefore, amount invested at 9% = $5,000
Thus, interest = $5,000
9% = $450
Amount invested at 8% interest = $8,000 - $5,000 = $3,000
Interest thereon, = $3,000
8% = $240
Therefore, final answer
$3,000