Volume of pyramid base 5 by 3 height 8

Step by step

The question

Question: find the volume of a pyramid with a rectangle base 5 by 3 and height 8.

1 Area of the base

The base is a rectangle, 5 by 3.

Its area is length times width: A = 5 × 3.

5 times 3 is 15.

So the base is A = 15 square units.

2 A third of the box

Draw a box around the pyramid, with the same base and the same height.

Fill the pyramid with sand 3 times.

That fills the box exactly.

So the pyramid is one third of the box.

The box is A times height.

So the pyramid is V = ⅓ × A × height.

Now put the numbers in: A = 15 and height = 8.

Keep the numbers small: divide 15 by 3 first.

15 divided by 3 is 5.

So V = 5 × 8.

5 times 8 is 40.

So the volume is 40 cubic units.

Let's look back.

First: area of the base.

Last: a third of the box.