Answer:
radius=11.5
diameter=23
Explanation:
The volume of a sphere is V=4/3 Pi r^3 
We can use this to solve for the radius. 
555.4= 4/3 (3.14)r^3
Solve for r how you would any other equation. Multiply 4/3 and 3.14.
555.4=4.187 r^3
Divide both sides by 4.187
132.65=r^3
To get rid of the ^3, find the cube root of both sides on a calcualtor. 
r= 11.5
The diameter is the radius time two. 
11.5 (2)=23. 
Hope this helps! 
Note: When I say both sides, I mean both sides of the = sign.