Here are some simple equations that can be a life saver with this stuff :
vol of a sphere =

Circumference = 

sorry this might not be very helpful. I haven't don't this since last year. You basically have to work backwards. so plug in 972 for V and then do (3/4)×3.14.
then take the answer u got for ^^ and divide it by 2? not sure.
 
        
             
        
        
        
6-z
Z-6 would be wrong because the question said start with 6
        
             
        
        
        
If it goes through the origin of a graph
        
             
        
        
        
I believe 20 is your answer. Tell me if I’m wrong.