in article , David Hare-Scott
at wrote on 6/26/03 4:37 PM:


"Repeating Decimal" wrote in message
...
The five gallon containers for plants always seemed small to me. Today
I got
to measure one of them. When I calculated the volume, it was 3.4
gallons not
five. Am I missing something? Is there a arcane standard for this?

Bill


This seems a large discrepancy even for a container not selling product
by volume. Which gallon (USA or Imperial) does the container use? How
did you do the sums to work out your figure?

David


I used the US gallon which is the smallest on my calculator. I US gallon is
231 cubic inches.

The formula I derived, although it should be available in reference books,
is:

V = (pi/3)*H*(R^2 +R*r+r^2).

H is the height of the conical frustum representing the shape of the
container. R and r are the upper and lower radii. H= 12 inches. R and r are
each *half* of the diameters 9.75 and 8.5 inches respectively. Out comes
3.4Gal.

Bill