Answer:
The volume of the rock is 13.368 cubic feet.
Step-by-step explanation:
The volume of the rock (
), measured in gallons, is equal to the volume of the fish aquarium without the decorative rock (
) minus the volume of the fish aquarium with the decorative rock (
), both measured in gallons.
Since the water flow is at constant rate, the volume of the rock is expressed by the following equation:
(1)
Where:
- Flow rate, measured in gallons per hour.
- Filling time of the fish aquarium without the decorative rock, measured in hours.
- Filling time of the fish aquarium with the decorative rock, measured in hours.
And the flow rate is:
The flow rate is 200 gallons per hour.
If we know that , 
and 
, then the volume of the rock is:
The volume of the rock is 13.368 cubic feet.
