The Volume of a Cylinder = π • r² • height
radius = 13.5 feet
volume = PI * 13.5^2 * 4 feet (the problem states it is to be filled to a depth of 4 feet)
volume = PI * 182.25 * 4
volume = 2,290 cubic feet
The hose delivers 80 cubic feet per hour so it will take:
2,290 / 80 = 28.625 hours
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The volume of the pool is:
volume = PI * 182.25 * 4.5
= 2,576.5 cubic feet