College

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

Answer :

The grain silo consists of two parts: a right circular cylinder and a hemisphere. We are given:

- Diameter of the silo: [tex]$4.4$[/tex] m (which gives the radius [tex]$r$[/tex] as half of the diameter)
- Height of the cylindrical portion: [tex]$6.2$[/tex] m
- Use [tex]$3.14$[/tex] for [tex]$\pi$[/tex]

Step 1. Calculate the radius.

Since the diameter is [tex]$4.4$[/tex] m, the radius is
[tex]$$
r = \frac{4.4}{2} = 2.2 \text{ m}.
$$[/tex]

Step 2. Volume of the cylindrical portion.

The formula for the volume of a cylinder is
[tex]$$
V_{\text{cyl}} = \pi r^2 h.
$$[/tex]
Substitute [tex]$r = 2.2$[/tex] m and [tex]$h = 6.2$[/tex] m into the formula:
[tex]$$
V_{\text{cyl}} = 3.14 \times (2.2)^2 \times 6.2.
$$[/tex]

First, compute the square of the radius:
[tex]$$
(2.2)^2 = 4.84.
$$[/tex]

Thus,
[tex]$$
V_{\text{cyl}} = 3.14 \times 4.84 \times 6.2 \approx 94.22512 \text{ m}^3.
$$[/tex]

Step 3. Volume of the hemispherical portion.

The volume of a sphere is
[tex]$$
V_{\text{sphere}} = \frac{4}{3} \pi r^3.
$$[/tex]
Since we have a hemisphere, its volume is half of that:
[tex]$$
V_{\text{hemi}} = \frac{1}{2} \times \frac{4}{3} \pi r^3 = \frac{2}{3} \pi r^3.
$$[/tex]

Substitute [tex]$r = 2.2$[/tex] m:
[tex]$$
V_{\text{hemi}} = \frac{2}{3} \times 3.14 \times (2.2)^3.
$$[/tex]

First, compute the cube of the radius:
[tex]$$
(2.2)^3 = 10.648.
$$[/tex]

Then,
[tex]$$
V_{\text{hemi}} \approx \frac{2}{3} \times 3.14 \times 10.648 \approx 22.28981 \text{ m}^3.
$$[/tex]

Step 4. Total Volume of the Silo.

Add the volume of the cylinder and the hemisphere:
[tex]$$
V_{\text{total}} = V_{\text{cyl}} + V_{\text{hemi}} \approx 94.22512 + 22.28981 \approx 116.51493 \text{ m}^3.
$$[/tex]

When rounded to the nearest tenth, the total volume is:
[tex]$$
116.5 \text{ m}^3.
$$[/tex]

Thus, the approximate total volume of the silo is [tex]$\boxed{116.5 \text{ m}^3}$[/tex].