



 
Hi Roger, By an "18 foot round hole" I assume you mean an 18 foot diameter. Thus the hole has the shape of a circular cylinder. The volume is then π r^{2} d where r is the radius and d is the depth. If you are ordering dirt you will need the volume in cubic yards (contractors call them yards) so change all the units to yards. There are 3 feet in a yard so the 18/2 = 9 foot radius is 9/3 = 3 yards. There are 36 inches in a yard so the hole is 16/36 yards deep. Thus the volume is
Penny  


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