This composite figure is made of two identical pyramids attached at their bases. Each pyramid has a height of 2 units.

Which expression represents the volume, in cubic units, of the composite figure?

A. [tex]\frac{1}{2}\left(\frac{1}{3}(5)(0.25)(2)\right)[/tex]
B. [tex]\frac{1}{2}\left(\frac{1}{3}(5)(0.25)(4)\right)[/tex]
C. [tex]2\left(\frac{1}{3}(5)(0.25)(2)\right)[/tex]
D. [tex]2\left(\frac{1}{3}(5)(0.25)(4)\right)[/tex]



Answer :

To find the volume of the composite figure, which is made up of two identical pyramids attached at their bases, we will follow these steps:

1. Determine the base area and height of one pyramid:
- Each pyramid has a height of [tex]\(2\)[/tex] units.
- The base area of each pyramid is given by multiplying the base length by its width. Since it gives [tex]\(5 \times 0.25\)[/tex] square units, the base area is [tex]\(1.25\)[/tex] square units.

2. Calculate the volume of one pyramid:
- The formula for the volume [tex]\(V\)[/tex] of a pyramid is:
[tex]\[ V = \frac{1}{3} \times \text{Base Area} \times \text{Height} \][/tex]
- Substitute the known values:
[tex]\[ V = \frac{1}{3} \times 1.25 \times 2 = 0.8333333333333333 \, \text{cubic units} \][/tex]

3. Determine the volume of the entire composite figure:
- There are two identical pyramids, so the total volume is:
[tex]\[ \text{Total Volume} = 2 \times V = 2 \times 0.8333333333333333 = 1.6666666666666665 \, \text{cubic units} \][/tex]

4. Analyze each given expression to find which correctly represents the volume of the composite figure:

- [tex]\(\frac{1}{2}\left(\frac{1}{3}(5)(0.25)(2)\right)\)[/tex]:
[tex]\[ = \frac{1}{2} \left(\frac{1}{3} \times 5 \times 0.25 \times 2\right) = \frac{1}{2} \times 0.8333333333333333 = 0.41666666666666663 \, \text{cubic units} \][/tex]

- [tex]\(\frac{1}{2}\left(\frac{1}{3}(5)(0.25)(4)\right)\)[/tex]:
[tex]\[ = \frac{1}{2} \left(\frac{1}{3} \times 5 \times 0.25 \times 4\right) = \frac{1}{2} \times 1.6666666666666665 = 0.8333333333333333 \, \text{cubic units} \][/tex]

- [tex]\(2\left(\frac{1}{3}(5)(0.25)(2)\right)\)[/tex]:
[tex]\[ = 2 \left(\frac{1}{3} \times 5 \times 0.25 \times 2\right) = 2 \times 0.8333333333333333 = 1.6666666666666665 \, \text{cubic units} \][/tex]

- [tex]\(2\left(\frac{1}{3}(5)(0.25)(4)\right)\)[/tex]:
[tex]\[ = 2 \left(\frac{1}{3} \times 5 \times 0.25 \times 4\right) = 2 \times 1.6666666666666665 = 3.333333333333333 \, \text{cubic units} \][/tex]

Based on our analysis, the expression that correctly represents the volume of the composite figure is:
[tex]\[ 2\left(\frac{1}{3}(5)(0.25)(2)\right) \][/tex]

This is the expression that matches the total volume of [tex]\(1.6666666666666665\)[/tex] cubic units.