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, and 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-h}{3.14}}, r=8.22[/tex] feet

E. [tex]r=\sqrt{\frac{V}{3.14 h}}(3), r=8.71[/tex] feet

Answer :

To solve the problem of finding the radius of the conical water reservoir, we'll use the formula for the volume of a cone. The formula for the volume [tex]\( V \)[/tex] of a cone is given by:

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

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

We know the following from the problem:
- The volume [tex]\( V = 225 \)[/tex] cubic feet
- The height [tex]\( h = 8.5 \)[/tex] feet

We need to determine the radius [tex]\( r \)[/tex]. To do this, we can rearrange the formula to solve for [tex]\( r \)[/tex]:

1. Rearrange the volume formula to solve for [tex]\( r^2 \)[/tex]:
[tex]\[ V = \frac{1}{3} \pi r^2 h \][/tex]

Multiply both sides by 3 to eliminate the fraction:
[tex]\[ 3V = \pi r^2 h \][/tex]

2. Divide both sides by [tex]\( \pi h \)[/tex] to isolate [tex]\( r^2 \)[/tex]:
[tex]\[ r^2 = \frac{3V}{\pi h} \][/tex]

3. Take the square root of both sides to solve for [tex]\( r \)[/tex]:
[tex]\[ r = \sqrt{\frac{3V}{\pi h}} \][/tex]

Now, substitute the given values (use 3.14 for [tex]\( \pi \)[/tex]):

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

When calculated, this gives us a radius of approximately 5.03 feet.

Thus, the correct formula to determine the radius of the water reservoir is:

[tex]\[ r = \sqrt{\frac{3V}{3.14 \times h}} \][/tex]

And the radius, rounded to the nearest hundredth of a foot, is 5.03 feet.