High School

A grain silo is composed of a cylinder and a hemisphere. The diameter is 4.4 meters, and the height of its cylindrical portion is 6.2 meters.

What is the approximate total volume of the silo? Use 3.14 for [tex]\pi[/tex] and round the answer to the nearest tenth of a cubic meter.

A. 37.1 [tex]m^3[/tex]
B. 71.9 [tex]m^3[/tex]
C. 116.5 [tex]m^3[/tex]
D. 130.8 [tex]m^3[/tex]

Answer :

To find the total volume of the grain silo, which is composed of a cylindrical portion and a hemispherical portion on top, we'll calculate the volume for each part separately and then add them together.

### Step 1: Calculate the Volume of the Cylindrical Portion

1. Identify the dimensions of the cylinder:
- Diameter = 4.4 meters.
- Radius = Diameter / 2 = 4.4 / 2 = 2.2 meters.
- Height of the cylinder = 6.2 meters.

2. Use the formula for the volume of a cylinder:
[tex]\[
\text{Volume of the cylinder} = \pi \times (\text{radius}^2) \times \text{height}
\][/tex]

3. Plug in the values:
[tex]\[
\text{Volume of the cylinder} = 3.14 \times (2.2)^2 \times 6.2
\][/tex]

4. Calculate the result:
- Calculate [tex]\((2.2)^2 = 4.84\)[/tex].
- Multiply: [tex]\(3.14 \times 4.84 \times 6.2 \approx 94.2 \text{ cubic meters}\)[/tex].

### Step 2: Calculate the Volume of the Hemispherical Portion

1. Identify the radius of the hemisphere (same as the cylinder's radius):
- Radius = 2.2 meters.

2. Use the formula for the volume of a hemisphere:
[tex]\[
\text{Volume of the hemisphere} = \frac{2}{3} \times \pi \times (\text{radius}^3)
\][/tex]

3. Plug in the values:
[tex]\[
\text{Volume of the hemisphere} = \frac{2}{3} \times 3.14 \times (2.2)^3
\][/tex]

4. Calculate the result:
- Calculate [tex]\((2.2)^3 = 10.648\)[/tex].
- Multiply: [tex]\(\frac{2}{3} \times 3.14 \times 10.648 \approx 22.3 \text{ cubic meters}\)[/tex].

### Step 3: Calculate the Total Volume of the Silo

1. Add the volumes of the cylinder and the hemisphere:
[tex]\[
\text{Total Volume} = 94.2 + 22.3
\][/tex]

2. Calculate the result:
- [tex]\(\text{Total Volume} = 116.5 \text{ cubic meters}\)[/tex].

Therefore, the approximate total volume of the silo is 116.5 cubic meters.