For this case, the first thing to do is find the volume of the tank.
We have then:
V = (12) * (9) * (8)
V = 864 feet ^ 3
Then, the cost of filling half the tank is given by:
C = (1/2) * (1.82) * (864)
C = 786.24 $
Answer:
It costs to fill the tank to one-half of its capacity about:
C = 786.24 $