I won't even pretend to know the answer, but here is something I found that may help..........
The volume of a circular cylinder of height h and radius r is
pi x r 2 x h
If you stand your hose on end you have a circular cylinder of height 500 feet and radius of one-half of 3/4 inches which is 3/8 inches. We need to settle on the units to use so let's use feet. Thus the cylinder has a radius of 3/8x12 = 3/96 = 1/32 inches.
Hence the volume of the hose is
pi x r 2 x h = 3.1416 x ( 1/32) 2 x 500 = 1.534 cubic feet
This is the link http://mathcentral.uregina.ca/QQ/databa ... avid2.html