Question

If h = 9 units and r = 3 units, what is the volume of the cone shown above?
Use 3.14 for pie
A.
28.26 cubic units
B.
254.34 cubic units
C.
9.42 cubic units
D.
84.78 cubic units

Answer 1

To find the volume of a cone, you can use the formula:

\[
V = \frac{1}{3} \pi r^2 h
\]

where \( V \) is the volume, \( r \) is the radius, and \( h \) is the height of the cone.

Given:
- \( h = 9 \) units
- \( r = 3 \) units
- Use \( \pi \approx 3.14 \)

Now, plug in the values into the formula:

\[
V = \frac{1}{3} \times 3.14 \times (3^2) \times 9
\]

Calculating step by step:

1. Calculate \( r^2 \):
\[
3^2 = 9
\]

2. Now substitute \( r^2 \) into the volume equation:
\[
V = \frac{1}{3} \times 3.14 \times 9 \times 9
\]

3. Calculate \( 9 \times 9 \):
\[
9 \times 9 = 81
\]

4. Now substitute this back into the volume equation:
\[
V = \frac{1}{3} \times 3.14 \times 81
\]

5. Calculate \( 3.14 \times 81 \):
\[
3.14 \times 81 = 254.34
\]

6. Finally, calculate \( \frac{1}{3} \times 254.34 \):
\[
\frac{254.34}{3} = 84.78
\]

So, the volume of the cone is:

\[
V = 84.78 \text{ cubic units}
\]

Thus, the answer is **D. 84.78 cubic units**.