College

You work for a store that sells built-to-order water reservoirs. Your manager asks you to visit a small business to measure a damaged conical water reservoir for replacement. The label on the water reservoir indicates the following specifications:

- The height is 8.5 feet.
- When full, the water reservoir holds 225 cubic feet of water.

Which formula will determine the radius of the water reservoir? Rounded to the nearest hundredth of a foot, what is the radius of the water reservoir?

A. [tex]r=\frac{\sqrt{V}}{3.14 h}, r=0.56[/tex] feet
B. [tex]r=\frac{3 \sqrt{V}}{3.14 h}, r=1.69[/tex] feet
C. [tex]r=\sqrt{\frac{3 V}{3.14 h}}, r=5.03[/tex] feet
D. [tex]r=\sqrt{\frac{3 V-\pi}{3.14}}, r=8.22[/tex] feet
E. [tex]r=\sqrt{\frac{V}{3.14 n}}(3), r=8.71[/tex] feet

Answer :

To find the radius of the conical water reservoir, we'll use the formula for the volume of a cone. The formula is:

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

Where:
- [tex]\( V \)[/tex] is the volume of the cone,
- [tex]\( r \)[/tex] is the radius of the base of the cone,
- [tex]\( h \)[/tex] is the height of the cone,
- [tex]\( \pi \)[/tex] is approximately 3.14.

We know from the problem that:
- The volume of the reservoir [tex]\( V \)[/tex] is 225 cubic feet,
- The height [tex]\( h \)[/tex] is 8.5 feet.

We need to solve for [tex]\( r \)[/tex], the radius of the base:

1. Rearrange the formula to solve for [tex]\( r^2 \)[/tex]:

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

2. Substitute the known values into the formula:

[tex]\[ r^2 = \frac{3 \times 225}{3.14 \times 8.5} \][/tex]

3. Calculate the value on the right side:

[tex]\[ r^2 = \frac{675}{26.69} \][/tex]

4. Simplify the division:

[tex]\[ r^2 \approx 25.30 \][/tex]

5. Take the square root to solve for [tex]\( r \)[/tex]:

[tex]\[ r = \sqrt{25.30} \][/tex]

6. Find the square root:

[tex]\[ r \approx 5.03 \][/tex]

Therefore, the radius of the water reservoir, rounded to the nearest hundredth of a foot, is approximately 5.03 feet. This matches the formula [tex]\( r = \sqrt{\frac{3V}{3.14h}} \)[/tex], so the correct option is:

[tex]\[ r = \sqrt{\frac{3V}{3.14h}}, \text{ with } r = 5.03 \text{ feet} \][/tex]