Question

A circular asparagus bed with a diameter of 6 ft is to be topped with screened organic compost to a depth of 2 ft. If compost costs $1.59 per cubic foot, how much will this cost? Compost is only sold in whole numbers of cubic feet.

Answer 1

About $89.91

Explanation:

The screening of compost creates a "cylinder" on top of the circular asparagus bed.

The volume of a cylinder is
`\pi r^2 h`

Where r is the radius [6/2 = 3]

h is the "depth" [h=2]

Now, the volume is:

`\pi r^2 h\\=\pi (3)^2 (2) \\=56.55`

We need 56.55 cubic feet, but it's not sold in fractional amount, so we will need 57 cubic feet of it.

Cost 1.59 per cubic feet, so we need

1.59 * 56.55 = $89.91