Answer:
Volume, 
Step-by-step explanation:
It is given that,
Diameter of spherical boulder is 18 ft
Weight of spherical boulder is 8 tons.
We need to find the volume of spherical boulder. The formula of the volume of sphere is given by :

r is radius of spherical boulder, r = 9 ft
Substituting all values in above formula :

The volume of spherical boulder is
.