"Richard Riley" wrote in message
...
On Sat, 30 Apr 2005 00:26:32 -0400, "W P Dixon"
wrote:

:Ok Guys and Gals,
: I do not remember the formula for this to save my life, so I will see
if
:yall can come up with it. Yes I did check on the web, but did not see the
:formula I need.
: I want to figure the volume of a gas tank that will not be round or
:square, It will have five sides and then the two ends of the tank. With
one
:end being larger than the other. I would give exact measurements , but
being
:as I don't know what they will be yet I can't:} I need to find the right
:volume in order to get the right measurement . Oh the dilemma !
: Be gentle math wizards it's been 25 years since I have had to do
this!
:

I'm not engineer, and I'm not currently playing one on TV, but I think
it's straightforward. Just so we're clear, I'm assuming -

Each end is a pentagon, each one of *it's* sides is equal length. The
two ends are parallel to each other. One pentagon is larger than the
other. They are perpendicular to a line drawn from the center of one
to the center of the other.

First, find the area of the large pentagon. The formula is

(the length of one side) squared * 1.7

Then multiply by the length of the tank to get the volume if both the
ends were the size of the large one.

Then do the same thing with the small end.

Now you have 2 volumes. Add them together, divide by 2.

So, if one end is a pentagon with sides that are 8 inches long, and
the other has sides that are 6 inches, and it's 24" long

Area of end one - 108.8
Area of end two - 61.2

Volume 1 2611.2
Volume 2 1468.8

Average 2040

Total 8.83 gallons.

This looks like the winning formula to me.