A rectangular pyramid and rectangular prism have congruent bases of 4 in by 5 in. If the volume of the pyramid is 40 in (3 sq) and the prism is 120 in (3sq) what is the height?

1 answer

The volume \( V \) of a pyramid is calculated using the formula:

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

The volume \( V \) of a rectangular prism is calculated using the formula:

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

Step 1: Calculate the Base Area

For both the pyramid and prism, the base is a rectangle with dimensions 4 inches and 5 inches. Thus, the base area \( A \) is:

\[ A = \text{Length} \times \text{Width} = 4 , \text{in} \times 5 , \text{in} = 20 , \text{in}^2 \]

Step 2: Calculate the Height of the Pyramid

We know the volume of the pyramid is given as 40 in³. Using the volume formula for the pyramid:

\[ 40 = \frac{1}{3} \times 20 \times h \]

To find the height \( h \), we can rearrange the equation:

\[ 40 = \frac{20h}{3} \]

Multiplying both sides by 3:

\[ 120 = 20h \]

Now, divide both sides by 20:

\[ h = \frac{120}{20} = 6 , \text{in} \]

Step 3: Calculate the Height of the Prism

We know the volume of the prism is given as 120 in³. Using the volume formula for the prism:

\[ 120 = 20 \times H \]

To find the height \( H \), we rearrange the equation:

\[ H = \frac{120}{20} = 6 , \text{in} \]

Summary

The height of both the rectangular pyramid and the rectangular prism is:

\[ \text{Height} = 6 , \text{in} \]