Question 523765
Volume of sphere = 4/3 *pi*r^3

Volume = 4/3 *pi*3^3
Volume = 113.09 

this weighs 1.67 lbs

1.67 lbs -------------- 113.09
45 lb------------------x
x= 45*113.09/1.67

3047.33 is the volume

V= (4/3)*pi*r^3
3V/4*pi=r^3
3*3047.33/4*pi=r^3

r^3=7180.33
r = cuberoot(7180.33)
r=19.29 in