I will drill nine holes in the ground. Each one will be eight inches in diameter and four feet deep, forming a cylinder. To find the volume of a cylinder, we find the area of the circle and then multiply that by the height.

Question 1: What is the area of each 8-inch circle, measured in square inches? To find that, we need its radius, so what is half of 8 inches?
Remember, A = (3.14)(radius)(radius)

Question 2: Measured in square feet, what is the area? To find that, divide the area measured in square inches by 144, which is the number of square inches in one square foot.

Question 3: What is the volume of each hole, measured in cubic feet? To find that, multiply the area of the circle, measured in square feet, by the height of the cylinder (four feet).

Question 4: What is the total volume of the nine cylinders? To find that, multiply the volume of one cylinder by nine.

Question 5: Since concrete is ordered in cubic yards, what is the total volume measured in cubic yards? One cubic yard contains 3x3x3=27 cubic feet, so divide your answer to question 4 by 27.