GED Math : Geometry and Graphs

Study concepts, example questions & explanations for GED Math

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Example Questions

Example Question #1 : Volume Of A Cylinder

A water tank takes the shape of a closed cylinder whose exterior has height 30 feet and a base with radius 10 feet; the tank is three inches thick throughout. To the nearest hundred, how many cubic feet of water does the tank hold?

You may use 3.14 for .

Possible Answers:

Correct answer:

Explanation:

Three inches is equal to 0.25 feet, so the height of the interior of the tank is

 inches.

The radius of the interior of the tank is 

 inches.

The amount of water the tank holds is the volume of the interior of the tank, which is

 cubic feet.

This rounds to 8,800 cubic feet.

Example Question #1 : Volume Of A Cylinder

Barrel

The above diagram is one of a cylindrical tub. The company wants to make a cylindrical tub with three times the volume, but whose base is only twice the radius. How high should this new tub be?

Possible Answers:

Correct answer:

Explanation:

The volume of the given tub can be expressed using the following formula, setting  and :

 cubic inches.

The new tub should have three times this volume, or

 cubic inches.

The radius is to be twice that of the above tub, which will be 

 inches.

The height can therefore be calculated as follows:

 inches

Example Question #3 : Volume Of A Cylinder

Barrel

Refer to the cylinder in the above diagram. 

A cone has twice the volume and twice the height of the cylinder. What is the radius of the base of the cone (nearest tenth of an inch, if applicable)?

Possible Answers:

Correct answer:

Explanation:

The formula for the volume of the cylinder is

where  and  are the base radius and height of the cylinder.

 

Set  in the formula to find the volume of the cylinder:

 

The cylinder will have volume twice this, or , and height twice the height of the cylinder, which is 80 inches.

The formula for the volume of the cone is

,

so we set  and  and solve for :

 inches.

Example Question #601 : Geometry And Graphs

Barrel

The above diagram is one of a cylindrical tub. The tub is holding water at 40% capacity. To the nearest cubic foot, how much more water can it hold?

Possible Answers:

Correct answer:

Explanation:

The volume of the cylinder can be calculated using the following formula, setting  and :

 cubic inches.

The tub is 40% full, so it is 60% empty; it can hold

 more cubic inches of water.

The problem asks for the number of cubic feet, so divide by the cube of 12, or 1,728:

The correct response is 27 cubic feet.

Example Question #601 : Geometry And Graphs

A circular swimming pool has diameter 40 feet and depth six feet throughout. How many cubic feet of water does it hold? (nearest cubic foot)

Use 3.14 as the value of .

Possible Answers:

Correct answer:

Explanation:

The pool can be seen as a cylinder with depth (or height) six feet and a base with diameter 40 feet - and radius half this, or 20 feet. The capacity of the pool is the volume of this cylinder, which is

 cubic feet.

Example Question #3 : Volume Of A Cylinder

A circular swimming pool has diameter 20 meters and depth 2.5 meters throughout. How many cubic meters of water does it hold?

Use 3.14 for .

Possible Answers:

Correct answer:

Explanation:

The pool can be seen as a cylinder with depth (or height) 2.5 m, a base with diameter 20 m, and a radius of half this, or 10 m. The capacity of the pool is the volume of this cylinder, which is

 cubic meters.

Example Question #2 : Volume Of A Cylinder

Find the volume of a cylinder with a radius of 2, and a height of 11.

Possible Answers:

Correct answer:

Explanation:

Write the volume for the cylinder.

Substitute the dimensions.

The answer is:  

Example Question #1 : Volume Of A Cylinder

Find the volume of a cylinder with a radius of 2, and a height of 15.

Possible Answers:

Correct answer:

Explanation:

write the formula for the volume of a cylinder.

Substitute the radius and height.

The answer is:  

Example Question #11 : Volume Of A Cylinder

If the circular base area of a cylinder is , what is the volume of the cylinder if the height is ?

Possible Answers:

Correct answer:

Explanation:

Write the formula for the volume of the cylinder.

The area of the circle is .

We can replace this term with .

Substitute the known terms.

The volume is:  

Example Question #12 : Volume Of A Cylinder

Find the volume of a cylinder with the following measurements:

Diameter:  8in

Height:  12in

Possible Answers:

Correct answer:

Explanation:

To find the volume of a cylinder, we will use the following formula:

where r is the radius, and h is the height of the cylinder.

Now, we know the diameter of the cylinder is 8in. We also know the diameter is two times the radius. Therefore, the radius is 4in. 

We know the height of the cylinder is 12in.

Knowing all of this, we can substitute into the formula. We get

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