We are given the following values:
Volume of fish tank = 30 cubic feet
Density of fish = 0.3 fish / 1 cubic feet
To solve for the number of fish in the tank, all we have to do is to multiply the given values such that in the units only the fish will remain. Therefore the number of fish inside the tank is calculated as:
number of fish in the tank = Volume of fish tank * Density of fish
number of fish in the tank = (30 cubic feet) (Density of fish = 0.3 fish / 1 cubic feet)
number of fish in the tank = 9 fish
Therefore there are only a total of 9 fish inside the tank.
Answer: C. 9