A cylindrical vase has a diameter of 6 inches. At the bottom of the vase, there are 7 marbles, each with a diameter of 3 inches. The vase is filled with water up to a height of 12 inches.

Which of the following could be used to calculate the volume of water in the vase?

A. [tex]\pi(12 \text{ in})^2(3 \text{ in}) - 7\left(\frac{4}{3} \pi(1.5 \text{ in})^3\right)[/tex]

B. [tex]\pi(3 \text{ in})^2(12 \text{ in}) - 7\left(\frac{4}{3} \pi(1.5 \text{ in})^3\right)[/tex]

C. [tex]\pi(12 \text{ in})^2(3 \text{ in}) - 1.5\left(\frac{4}{3} \pi(7 \text{ in})^2\right)[/tex]

D. [tex]\pi(3 \text{ in})^2(12 \text{ in}) - 1.5\left(\frac{4}{3} \pi(7 \text{ in})^3\right)[/tex]



Answer :

Let's break down the steps to determine which formula calculates the volume of water in the vase:

1. Calculate the volume of the vase:

- The vase is a cylinder with a diameter of 6 inches and a height of 12 inches.
- The radius of the vase is half of the diameter:
[tex]\[ r_{\text{vase}} = \frac{6 \text{ inches}}{2} = 3 \text{ inches} \][/tex]
- The formula for the volume of a cylinder is [tex]\(V = \pi r^2 h\)[/tex], where [tex]\(r\)[/tex] is the radius and [tex]\(h\)[/tex] is the height.
- Substituting the radius and height:
[tex]\[ V_{\text{vase}} = \pi (3 \text{ inches})^2 (12 \text{ inches}) = \pi \times 9 \text{ in}^2 \times 12 \text{ in} = 108 \pi \text{ in}^3 \][/tex]

2. Calculate the volume of one marble:

- Each marble is a sphere with a diameter of 3 inches.
- The radius of each marble is half of the diameter:
[tex]\[ r_{\text{marble}} = \frac{3 \text{ inches}}{2} = 1.5 \text{ inches} \][/tex]
- The formula for the volume of a sphere is [tex]\(V = \frac{4}{3} \pi r^3\)[/tex], where [tex]\(r\)[/tex] is the radius.
- Substituting the radius:
[tex]\[ V_{\text{marble}} = \frac{4}{3} \pi (1.5 \text{ inches})^3 = \frac{4}{3} \pi \times 3.375 \text{ in}^3 = 4.5 \pi \text{ in}^3 \][/tex]

3. Calculate the total volume of the 7 marbles:

[tex]\[ V_{\text{total marbles}} = 7 \times V_{\text{marble}} = 7 \times 4.5 \pi \text{ in}^3 = 31.5 \pi \text{ in}^3 \][/tex]

4. Calculate the volume of water in the vase:

- The volume of water is the volume of the vase minus the total volume of the marbles.
- Substituting the volumes:
[tex]\[ V_{\text{water}} = V_{\text{vase}} - V_{\text{total marbles}} = 108 \pi \text{ in}^3 - 31.5 \pi \text{ in}^3 = 76.5 \pi \text{ in}^3 \][/tex]

Now let's compare this to the provided options:

- First option: [tex]\(\pi(12 \text{ in})^2(3 \text{ in}) - 7\left(\frac{4}{3} \pi(1.5 \text{ in})^3\right)\)[/tex]

This doesn't match our expression for the vase volume calculation or marble volume correctly.

- Second option: [tex]\(\pi(3 \text{ in})^2(12 \text{ in}) - 7\left(\frac{4}{3} \pi(1.5 \text{ in})^3\right)\)[/tex]

This matches our calculations exactly:
- The volume of the vase [tex]\(\pi (3 \text{ in})^2 (12 \text{ in})\)[/tex]
- The total volume of the marbles [tex]\(7\left(\frac{4}{3} \pi (1.5 \text{ in})^3\right)\)[/tex]
This is the correct formula.

- Third option: [tex]\(n(12 \text{ in})^2(3 \text{ in}) - 1.5\left(\frac{4}{3} \pi(7 \text{ in})^2\right)\)[/tex]

This doesn't match our calculation at all.

- Fourth option: [tex]\(\pi(3 \text{ in})^2(12 \text{ in}) - 1.5\left(\frac{4}{3} \pi(7 \text{ in})^3\right)\)[/tex]

This also doesn't align with our values.

So, the correct formula is:

[tex]\[ \pi(3 \text{ in})^2(12 \text{ in})-7\left(\frac{4}{3} \pi(1.5 \text{ in})^3\right) \][/tex]