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Question
Mei Li measures a cube and a square-based pyramid and finds that the pyramid has the same height and base area as the cube. She also calculates that the volume of the cube is 9 cubic meters. What is the volume of the pyramid?(1 point)
Responses

6m3
6m cubed

3 m3
3 m cubed

30m3
30m cubed

1m3

1 answer

To find the volume of the square-based pyramid, we can use the formula for the volume of a pyramid, which is given by:

\[ V = \frac{1}{3} \times \text{Base Area} \times \text{Height} \]

We know the following:

  1. The base area of the pyramid is equal to the base area of the cube.
  2. The height of the pyramid is equal to the height of the cube.
  3. The volume of the cube is 9 cubic meters.

Let's find the side length of the cube first. The volume \( V \) of a cube is given by:

\[ V = \text{side length}^3 \]

If the volume of the cube is 9 m³, then:

\[ \text{side length}^3 = 9 \quad \Rightarrow \quad \text{side length} = \sqrt[3]{9} \]

Now, the volume of a cube also gives us the base area (which is side length squared). Therefore, the base area of the cube (and the pyramid) is:

\[ \text{Base Area} = \text{side length}^2 = (\sqrt[3]{9})^2 = 9^{2/3} = 3^{4/3} \]

The height of the cube would be equal to the side length:

\[ \text{Height} = \sqrt[3]{9} \]

Now, substituting these into the volume formula for the pyramid:

\[ V_{\text{pyramid}} = \frac{1}{3} \times (3^{4/3}) \times (\sqrt[3]{9}) \]

Let's simplify:

\[ = \frac{1}{3} \times 3^{4/3} \times 3^{2/3} = \frac{1}{3} \times 3^{(4/3) + (2/3)} = \frac{1}{3} \times 3^{6/3} = \frac{1}{3} \times 3^2 = \frac{1}{3} \times 9 = 3 \]

So, the volume of the square-based pyramid is \( 3 , \text{m}^3 \).

Thus, the correct response is:

3 m³