about 432 cubic inches
.21 yards of sand will fill an area 115 inches by 67 inches to a depth of 2.5 inches.
22/7x6x6x6 cubic inches
None, as a hole which is 6 inches wide and 42 inches long has no depth and thus no volume.
6,400 ft3
25 feet is equal to 300 inches. The radius of a hole is half its diameter, which equals 4 inches. The volume of the cylinder is given by the formula v = [Pi]r2h, so the volume of your hole is 3.14 * 16 * 300 = 15080 cubic inches. There are 1728 cubic inches to the cubic foot, so you'll need about 8.75 cubic feet of concrete, which is about a third of a yard. (More exactly, that's a cubic yard, but concrete guys just say "yard.")
18.6240 yd³
To calculate the volume of concrete needed to fill a hole with a diameter of 12 inches and a depth of 24 inches, first convert the dimensions to feet: the diameter is 1 foot and the depth is 2 feet. The radius is 0.5 feet. Using the formula for the volume of a cylinder (V = πr²h), the volume is approximately 3.14 × (0.5)² × 2 = 1.57 cubic feet. Therefore, you need about 1.57 cubic feet of concrete to fill the hole.
To install a mailbox post correctly, dig a hole at least 24 inches deep, place the post in the hole, and fill it with concrete. Make sure the post is level and allow the concrete to set before attaching the mailbox.
.21 yards of sand will fill an area 115 inches by 67 inches to a depth of 2.5 inches.
42 cubic feet or 1.56 yards.
The recommended method for installing a concrete footing for a 6x6 post is to dig a hole that is at least 12 inches in diameter and 24 inches deep. Place a cardboard tube form in the hole and fill it with concrete, making sure it is level. Insert a post anchor into the wet concrete and allow it to cure for at least 24 hours before attaching the post.
To calculate the amount of concrete needed to fill a 12-inch diameter hole that is 18 inches deep, first convert the measurements to feet: the diameter is 1 foot and the depth is 1.5 feet. The volume of a cylinder is given by the formula V = πr²h. The radius (r) is 0.5 feet, so the volume is approximately π(0.5)²(1.5) = about 1.18 cubic feet. Thus, you would need roughly 1.18 cubic feet of concrete to fill the hole.
22/7x6x6x6 cubic inches
None, as a hole which is 6 inches wide and 42 inches long has no depth and thus no volume.
6,400 ft3
To fill a 10-inch diameter sonotube that is 4 feet deep, you'll need to calculate the volume of the tube. The formula for the volume of a cylinder is V = πr²h. The radius is 5 inches (0.417 feet), so the volume is approximately 0.544 cubic feet. A typical bag of concrete (60 lbs) yields about 0.45 cubic feet, meaning you'll need about 1.2 bags of concrete to fill the sonotube completely. Therefore, you should plan on purchasing 2 bags to ensure you have enough material.
509.7 litres