Common Core: 7th Grade Math : Geometry

Study concepts, example questions & explanations for Common Core: 7th Grade Math

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Example Questions

Example Question #11 : Solve Problems Involving Area, Volume And Surface Area Of Two And Three Dimensional Objects: Ccss.Math.Content.7.G.B.6

7 24 25

The pictured right triangle has sides of 7, 24, and 25. What is the area of that triangle?

Possible Answers:

128

84

77

125

64

Correct answer:

84

Explanation:

The area of a triangle can be calculated using the formula \displaystyle Area = \frac{1}{2}(Base)(Height). Note that the height of any triangle is a perpendicular line between the base and its opposite angle; in a right triangle that's very convenient, because the right angle gives you that perpendicular relationship between two sides. So you can use 24 as the base and 7 as the height here.  That means that the area is:

\displaystyle Area =\frac{1}{2}(24)(7)=84

Example Question #1 : Finding Volume Of A Rectangular Prism

An aquarium is shaped like a perfect cube; the perimeter of each glass face is \displaystyle 8.4 meters. If it is filled to the recommended \displaystyle 90\% capacity, then, to the nearest hundred cubic liters, how much water will it contain? 

Possible Answers:

Insufficient information is given to answer the question.

\displaystyle 4\textup,000\textup{ L}

\displaystyle 4\textup,400\textup{ L}

\displaystyle 8\textup,300\textup{ L}

\displaystyle 9\textup,300\textup{ L}

Note:\displaystyle 1\textup{ cubic meter}= 1\textup{,}000\textup{ cubic liters}


Correct answer:

\displaystyle 8\textup,300\textup{ L}

Explanation:

A perfect cube has square faces; if a face has perimeter \displaystyle 8.4 meters, then each side of each face measures one fourth of this, or \displaystyle 2.1 meters. The volume of the tank is the cube of this, or

\displaystyle 2.1^{3} = 9.261 cubic meters.

Its capacity in liters is \displaystyle 9.261 \times 1,000 = 9,261 liters.

\displaystyle 90\% of this is 

\displaystyle 9,261 \times 0.9 = 8,335 liters. 

This rounds to\displaystyle 8\textup,300 liters, the correct response.

Example Question #2 : Finding Volume Of A Rectangular Prism

Calculate the volume of the provided figure.


11

Possible Answers:

\displaystyle 143\textup{ in}^3

\displaystyle 145\textup{ in}^3

\displaystyle 142\textup{ in}^3

\displaystyle 144\textup{ in}^3

\displaystyle 141\textup{ in}^3

Correct answer:

\displaystyle 144\textup{ in}^3

Explanation:

In order to solve this problem, we need to recall the volume formula for a rectangular prism:

\displaystyle V=l\times w\times h

Now that we have the correct formula, we can substitute in our known values and solve: 

\displaystyle V=9\times4\times4

\displaystyle V=144\textup{ in}^3

Example Question #1 : Finding Volume Of A Rectangular Prism

Calculate the volume of the provided figure.

12

Possible Answers:

\displaystyle 181\textup{ in}^3

\displaystyle 184\textup{ in}^3

\displaystyle 180\textup{ in}^3

\displaystyle 182\textup{ in}^3

\displaystyle 183\textup{ in}^3

Correct answer:

\displaystyle 180\textup{ in}^3

Explanation:

In order to solve this problem, we need to recall the volume formula for a rectangular prism:

\displaystyle V=l\times w\times h

Now that we have the correct formula, we can substitute in our known values and solve: 

\displaystyle V=12\times5\times3

\displaystyle V=180\textup{ in}^3

Example Question #1 : Finding Volume Of A Rectangular Prism

Calculate the volume of the provided figure.

10

Possible Answers:

\displaystyle 241\textup{ in}^3

\displaystyle 243\textup{ in}^3

\displaystyle 244\textup{ in}^3

\displaystyle 242\textup{ in}^3

\displaystyle 240\textup{ in}^3

Correct answer:

\displaystyle 240\textup{ in}^3

Explanation:

In order to solve this problem, we need to recall the volume formula for a rectangular prism:

\displaystyle V=l\times w\times h

Now that we have the correct formula, we can substitute in our known values and solve: 

\displaystyle V=10\times4\times6

\displaystyle V=240\textup{ in}^3

Example Question #1 : Finding Volume Of A Rectangular Prism

A rectangular prism has the following dimensions:

Length: \displaystyle 6.3 \:cm

Width: \displaystyle 6.3 \:cm

Height: \displaystyle 2.1 \:cm

Find the volume.

Possible Answers:

\displaystyle 83.4\:cm^3

\displaystyle 84.3\:cm^3

\displaystyle 83.3\:cm^3

\displaystyle 84.9\:cm^3

\displaystyle 83.8\:cm^3

Correct answer:

\displaystyle 83.3\:cm^3

Explanation:

Given that the dimensions are: \displaystyle 6.3 \:cm, \displaystyle 6.3 \:cm, and \displaystyle 2.1 \:cm and that the volume of a rectangular prism can be given by the equation:

\displaystyle v=l \cdot w \cdot h, where \displaystyle l is length, \displaystyle w is width, and \displaystyle h is height, the volume can be simply solved for by substituting in the values.

\displaystyle V = (6.3)(6.3)(2.1)

\displaystyle V = (39.69)(2.1)

\displaystyle V = 83.349\:cm^3

This final value can be approximated to \displaystyle 83.3\:cm^3.

Example Question #1 : Finding Volume Of A Rectangular Prism

Solve for the volume of a prism that is 4m by 3m by 8m. 

Possible Answers:

\displaystyle V = 144 m^3

\displaystyle V=88m^3

\displaystyle V = 136 m^3

\displaystyle V = 96 m^3

\displaystyle V = 102 m^3

Correct answer:

\displaystyle V = 96 m^3

Explanation:

The volume of the rectangle 

\displaystyle V = l*w*h 

so we plug in our values and obtain

\displaystyle V = 4*3*8

\displaystyle V = 96 m^3.

Example Question #91 : Geometry

The dimensions of Treasure Chest A are 39” x 18”. The dimensions of Treasure Chest B are  16” x 45”. Both are 11” high. Which of the following statements is correct?

Possible Answers:

Treasure Chest A and B can hold the same amount of treasure.

Treasure Chest A has the same surface area as Treasure Chest B.

Treasure Chest A can hold more treasure.

Treasure Chest B can hold more treasure.

There is insufficient data to make a comparison between Treasure Chest A and Treasure Chest B.

Correct answer:

Treasure Chest B can hold more treasure.

Explanation:

The volume of B is 7920 in3. The volume of A is 7722 in3. Treasure Chest B can hold more treasure.

Example Question #1 : Finding Volume Of A Rectangular Prism

A rectangular prism has a width of 3 inches, a length of 6 inches, and a height triple its length. Find the volume of the prism.

Possible Answers:

\displaystyle 324in^3

\displaystyle 420in^3

\displaystyle 38in^3

\displaystyle 27in^3

Correct answer:

\displaystyle 324in^3

Explanation:

A rectangular prism has a width of 3 inches, a length of 6 inches, and a height triple its length. Find the volume of the prism.

Find the volume of a rectangular prism via the following:

\displaystyle V=l*w*h

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

We know our length and width, and we are told that our height is triple the length, so...

\displaystyle h=3l=3*6in=18in

Now that we have all our measurements, plug them in and solve:

\displaystyle V=3in*6in*18in=324in^3

Example Question #91 : Geometry

Box

The above diagram shows a rectangular solid. The shaded side is a square. In terms of \displaystyle x, give the volume of the box.

Possible Answers:

\displaystyle 15x^{2}

\displaystyle 225x

\displaystyle 4x^{2} + 30 x

\displaystyle 60x + 450

Correct answer:

\displaystyle 225x

Explanation:

A square has four sides of equal length, as seen in the diagram below.

Box

The volume of the solid is equal to the product of its length, width, and height, as follows:

\displaystyle V = 15 \cdot 15 \cdot x =225 x.

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