Answer:
The total ammount in the compound interest account is $73325.30
Explanation:
The compound interest formula is given by:

A: Amount of money(Balance)
P: Principal(Initial deposit)
r: interest rate(as a decimal value)
n: number of times that interest is compounded per unit t
t: time the money is invested or borrowed for.
In our problem, we have that:
A = total amount
P = $9000
r = 0.12
n = 2(semiannually means twice a year)
t = 18
So:



The total ammount in the compound interest account is $73325.30