Answer:
48 square feet.
Step-by-step explanation:
A large dump truck will empty its full load of stone . 
Those rock forms a cone.
Height of cone = 9 feet
The truck holds 144 cubic feet of stone. 
So, amount of stone truck holds = Volume of cone 
Formula of volume of cone = 
Where 
            
So, volume of cone formed  = 
Since we know that amount of stone truck holds = Volume of cone formed





Thus the area of the circular base is 48 square feet.