The volume of a pyramid varies jointly with the base area of the pyramid and its height. The volume of one pyramid is 35

cubic inches when its base area is 15
square inches and its height is 7
inches. What is the volume of a pyramid with a base area of 36
square inches and a height of 5
inches?

The volume of the pyramid is blank cubic inches.

The solution is

1 answer

The volume \( V \) of a pyramid can be expressed with the formula:

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

We know that the volume varies jointly with the base area and height, so we can express this relationship as:

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

for some constant \( k \).

From the given information, the volume of one pyramid is 35 cubic inches with a base area of 15 square inches and a height of 7 inches. We can use this information to find \( k \):

\[ 35 = k \times 15 \times 7 \]

Calculating \( 15 \times 7 \):

\[ 15 \times 7 = 105 \]

Now, substituting that back into the equation:

\[ 35 = k \times 105 \]

To find \( k \), we divide both sides by 105:

\[ k = \frac{35}{105} = \frac{1}{3} \]

Now that we have \( k \), we can find the volume of a new pyramid with a base area of 36 square inches and a height of 5 inches. The volume will be:

\[ V = \frac{1}{3} \times 36 \times 5 \]

Calculating \( 36 \times 5 \):

\[ 36 \times 5 = 180 \]

Now substituting back into the volume equation:

\[ V = \frac{1}{3} \times 180 = 60 \]

Thus, the volume of the pyramid is:

\[ \text{The volume of the pyramid is } 60 \text{ cubic inches.} \]