When the pool is full to the rim, you'll have a cylinder of water. The diameter
of the cylinder is 15-ft, and the height of the cylinder is 42 inches.
Here are the tools you'll need:
-- Volume of a cylinder = (pi) (radius squared) (height)
-- Radius = 1/2 diameter = 7.5 feet
-- Keep everything in the same units. Depending on which unit
you prefer, 7.5 feet = 90 inches, and 42 inches = 3.5 feet.
I like inches and cubic inches, because I remember that
1 gallon = exactly 231 cubic inches.
Volume of the cylinder = (pi) (radius squared) (height)
Volume = (pi) (90 squared) (42) = (pi) (8,100) (42) = 1,068,769.8 cubic inches
1,068,769.8 / 231 = 4,626.7 gallons
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Slightly easier:
about 7.48 gallons = 1 cubic foot
Volume = (pi) (7.5-ft squared) (3.5-ft) = 618.5 cubic feet
(618.6 cubic-ft) x (7.48 gallons per cubic-ft) = 4,627.1 gallons
The results are not identical, but don't panic. They are equal
to within about 51 ounces (0.009 percent). The tanker will either
spill or evaporate more than that during the process of the delivery.
By the way ... you'd be wise not to install the pool on the second floor.
That much water weighs a little over 19.3 tons !
