Posted by Nancy on .
LPG is stored in highly insulated spherical vessels in most oil refineriesif.If the inside diameter of one of these tanks is 11.4ft, find it's volume. Report your answer to the nearest onetenth of a gal. Use r=3.14 and 1 cubic ft=7.5gal

geometry 
drwls,
The volume in ft^3 is
(pi/6)*D^3
if you use D = 11.4 ft
You do the conversion to gallons.
For the accuracy they desire, they should NOT be telling you to use 7.5 gal/ft^3 as the conversion factor and pi = 3.14.
I have no idea what you are using the symbol r for pi.