Answer:
$431.30
Explanation:
The Present value of deposit will be $8,500 * 9.4% discount rate at year 9.
PV = $8,500 * 1.094 ^ 9
PV = 19,079.84
The future value of the deposit will be,
FV = PV / ( 1 + r ) ^ n
FV = 19,079.84 / 1.088 ^ 9
FV = $8,931.30
The more deposit needed will be $8,500 - $8,931 = 431.30.