GED Math : Volume of a Rectangular Solid

Study concepts, example questions & explanations for GED Math

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Example Questions

Example Question #33 : 3 Dimensional Geometry

Tammy has an aquarium in the shape of a rectangular prism. The aquarium has the following dimensions: \(\displaystyle 12 in \times 16 in \times 30 in\). In order for her to properly clean the aquarium, she must remove two-thirds of the water in the aquarium. In cubic inches, how much water must she remove?

Possible Answers:

\(\displaystyle 1920\)

\(\displaystyle 3840\)

\(\displaystyle 2460\)

\(\displaystyle 3640\)

Correct answer:

\(\displaystyle 3840\)

Explanation:

Start by finding the volume of the rectangular prism.

\(\displaystyle \text{Volume}=\text{length}\times \text{width}\times \text{height}\)

For the given dimensions,

\(\displaystyle \text{Volume}=12\times 16 \times 30=5760\)

Since Tammy needs to remove two-thirds of the water, we will need to find two-thirds of the volume.

\(\displaystyle (5760)\frac{2}{3}=3840\)

Tammy must remove \(\displaystyle 3840in^3\) of water.

Example Question #34 : 3 Dimensional Geometry

If a brick is a rectangular sold, what is its volume if its base area is 4, and the height is 5?

Possible Answers:

\(\displaystyle 160\)

\(\displaystyle 80\)

\(\displaystyle 20\)

\(\displaystyle 40\)

\(\displaystyle 400\)

Correct answer:

\(\displaystyle 20\)

Explanation:

Write the formula for the area of a rectangular solid.

\(\displaystyle V =LWH\)

The base area consists of \(\displaystyle LW\), which means we can substitute the area as replacement of the two variables.

\(\displaystyle V =LWH = (4)(5) = 20\)

The answer is:  \(\displaystyle 20\)

Example Question #41 : 3 Dimensional Geometry

For an art project, Amy needs to paint a rectangular box with the dimensions \(\displaystyle 4in\times 6in \times 10in\) red, blue, and yellow. Each color must take up one-third of the painted surface. In square inches, how much blue paint is needed?

Possible Answers:

\(\displaystyle 78.33\)

\(\displaystyle 82.67\)

\(\displaystyle 66.33\)

\(\displaystyle 85.67\)

Correct answer:

\(\displaystyle 82.67\)

Explanation:

Since Amy is painting the outside of a box, we will need to find the surface area of the box.

Recall how to find the surface area of a rectangular prism:

\(\displaystyle \text{Surface Area}=2(wl+hl+hw)\), where \(\displaystyle w\) is the width, \(\displaystyle h\) is the height, and \(\displaystyle l\) is the length.

Because we are only interested in the amount of blue paint that Amy will be painting, we know that we will need to find one-third of the surface area.

\(\displaystyle \text{Area of Blue Paint}=\frac{\text{Surface Area}}{3}=\frac{2(wl+hl+hw)}{3}\)

Plug in the dimensions of the box to find the area of the blue paint.

\(\displaystyle \text{Area of Blue Paint}=\frac{2((4)(6)+(6)(10)+(4)(10))}{3}=\frac{248}{3}=82.67\)

Example Question #11 : Volume Of A Rectangular Solid

A rectangular prism has as its three dimensions \(\displaystyle x\)\(\displaystyle 2x\), and \(\displaystyle x+ 6\). Give its volume in terms of \(\displaystyle x\).

Possible Answers:

\(\displaystyle 2 x ^{3} +6x ^{2}\)

\(\displaystyle 2 x ^{3} +12 x ^{2}\)

\(\displaystyle 4x+6\)

\(\displaystyle 4x+12\)

Correct answer:

\(\displaystyle 2 x ^{3} +12 x ^{2}\)

Explanation:

The volume of a rectangular prism is equal to the product of its three dimensions, so here,

\(\displaystyle V= x \cdot 2x \cdot (x+6)\)

\(\displaystyle =2 \cdot x \cdot x \cdot (x+6)\)

\(\displaystyle =2 x ^{2} (x+6)\)

Apply the distribution property, multiplying \(\displaystyle 2x^{2}\) by each of the expressions in the parentheses:

\(\displaystyle V =2 x ^{2} \cdot x+2 x ^{2} \cdot 6\)

\(\displaystyle =2 x ^{2+1} +2 \cdot 6 \cdot x ^{2}\)

\(\displaystyle =2 x ^{3} +12 x ^{2}\)

Example Question #12 : Volume Of A Rectangular Solid

You are building a metal crate to hold fishing equipment. If the crate will be 1.5 ft long, 2 feet tall, and 5 feet wide, what will its volume be?

Possible Answers:

\(\displaystyle V=8.5ft^3\)

\(\displaystyle V=115ft^3\)

\(\displaystyle V=15ft^3\)

\(\displaystyle V=10.5ft^3\)

Correct answer:

\(\displaystyle V=15ft^3\)

Explanation:

You are building a metal crate to hold fishing equipment. If the crate will be 1.5 ft long, 2 feet tall, and 5 feet wide, what will its volume be?

We are asked to find the volume of a rectangular solid. In this case it is a metal crate, but it is essentially a rectangular solid. To find its volume, use the following formula:

\(\displaystyle V=l*w*h\)

Where, l, w, and h are the length, width and height.

\(\displaystyle V=1.5ft*2ft*5ft=1.5ft*10ft^2=15ft^3\)

\(\displaystyle V=15ft^3\)

 

 

Example Question #11 : Volume Of A Rectangular Solid

Prism

One cubic centimeter of pure iron is about \(\displaystyle 7.9 \textup{ grams}\) in mass. 

Using this figure, what is the mass, in kilograms, of the above iron bar?

Possible Answers:

\(\displaystyle 114\textup{ kg}\)

\(\displaystyle 568.8 \textup{ kg}\)

\(\displaystyle 11.4 \textup{ kg}\)

\(\displaystyle 56.8 8 \textup{ kg}\)

Correct answer:

\(\displaystyle 568.8 \textup{ kg}\)

Explanation:

First, convert the dimensions of the prism to centimeters. One meter is equal to 100 centimeters, so multiply by this conversion factor:

\(\displaystyle 0.8 \textup{ m } \times 100 \textup{ cm /m} = 80 \textup{ cm}\)

\(\displaystyle 0.3 \textup{ m } \times 100 \textup{ cm /m} =30 \textup{ cm}\)

The dimensions of the prism are 80 centimeters by 30 centimeters by centimeters; multiply these dimensions to find the volume:

\(\displaystyle V = 80 \textup{ cm} \times 30 \textup{ cm} \times 30 \textup{ cm}\)

\(\displaystyle = 72,000 \textup{ cm}^{3}\)

Using the given mass of 7.9 grams per cubic centimeter, multiply:

\(\displaystyle M = 72,000 \textup{ cm}^{3} \times 7.9 \textup{ g / cm}^{3} = 568,800 \textup{ g}\)

One kilogram is equal to 1,000 grams, so divide by this conversion factor:

\(\displaystyle M = 568,800 \textup{ g} \div 1,000 \textup{ g / kg} = 568.8 \textup{ kg}\),

the correct mass of the prism.

Example Question #11 : Volume Of A Rectangular Solid

Find the volume of a rectangular prism with the following dimensions: 6 ft by 12 ft by 4 ft.

Possible Answers:

\(\displaystyle 208 ft^3\)

\(\displaystyle 198 ft^3\)

\(\displaystyle 288 ft^3\)

\(\displaystyle 148 ft^3\)

Correct answer:

\(\displaystyle 288 ft^3\)

Explanation:

Find the volume of a rectangular prism with the following dimensions: 6 ft by 12 ft by 4 ft.

To find the volume of a rectangular prism, simply multiply the length by the width by the height.

\(\displaystyle V=l*w*h\)

So, plug in and multiply to get:

\(\displaystyle V=6ft*4ft*12ft=24ft^2*12ft=288ft^3\)

So, our answer is:

\(\displaystyle 288 ft^3\)

Coincidentally the same as our surface area

Example Question #11 : Volume Of A Rectangular Solid

What is the volume of a box with length of 3 feet, width of 5 feet, and height of 2 feet?

Possible Answers:

12 feet squared 

30 feet squared

10 feet squared

15 feet squared

7 feet squared 

Correct answer:

30 feet squared

Explanation:

The equation for the volume of a rectangular prism is

\(\displaystyle V=l\cdot w \cdot h\)

So we simply input our dimensions

\(\displaystyle V=5\cdot2\cdot3=30\)

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