Assuming the 28 feet refers to the diameter of the circle, the answer is 1231.5 cubic feet, approx.
About a ton.
33.5 cubic feet.
16.05
An area 10 foot x 10 foot is 100 square feet. 100 cubic feet of sand would cover it with a one foot deep layer of sand. If the sand needs to be 6 inches deep, then 50 cubic feet are be needed, or 25 cubic feet if the sand is to be 3 inches thick.
A circle that is 4 feet 6 inches in diameter has an area of: 15.904 square feet.
A circle with a radius of 80 inches has a circumference of 502.65 inches, which is equal to 41.8875 feet. Therefore, it is greater than a circle with a circumference of 40.5 feet.
Volume = 1240.5 = 24 cubic feet is needed
The circumference of a circle = pi*diameter. 6 feet 3 inches = 6.25 feet, pi*6.25 = 19.63495408 feet or the circumference of the circle is nearly 20 feet.
1 foot by 36 sq feet = 36 cubic feet of dirt is needed
Without depth, the circle is a flat figure without volume ... zero cubic units.
A circle with a radius of 80 inches has an area of 139.6 square feet A circle with a circumference of 40.5 feet has an area of 130.5 square feet
volume of soil needed = 38*5*1=190sq ft .12" = 1 feet