Common Core: 8th Grade Math : Geometry

Study concepts, example questions & explanations for Common Core: 8th Grade Math

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Example Questions

Example Question #171 : Geometry

The height of a cylinder is two times the length of the radius of the circular end of a cylinder. If the volume of the cylinder is , what is the height of the cylinder?

Possible Answers:

Correct answer:

Explanation:

The volume of a cylinder is:

 

where is the radius of the circular end of the cylinder and is the height of the cylinder.


Since , we can substitute that into the volume formula. So we can write:

 

So we get:

 

Example Question #172 : Geometry

The end (base) of a cylinder has an area of square inches. If the height of the cylinder is half of the radius of the base of the cylinder, give the volume of the cylinder.

Possible Answers:

Correct answer:

Explanation:

The area of the end (base) of a cylinder is , so we can write:

 

The height of the cylinder is half of the radius of the base of the cylinder, that means:

 

 

The volume of a cylinder is found by multiplying the area of one end of the cylinder (base) by its height:

or

Example Question #173 : Geometry

We have two right cylinders. The radius of the base Cylinder 1 is  times more than that of Cylinder 2, and the height of Cylinder 2 is 4 times more than the height of Cylinder 1. The volume of Cylinder 1 is what fraction of the volume of Cylinder 2?

Possible Answers:

Correct answer:

Explanation:

The volume of a cylinder is:

where is the volume of the cylinder,   is the radius of the circular end of the cylinder, and is the height of the cylinder.

 

So we can write:

 

and

 

Now we can summarize the given information:

 

Now substitute them in the formula:

 

Example Question #174 : Geometry

Two right cylinders have the same height. The radius of the base of the first cylinder is two times more than that of the second cylinder. Compare the volume of the two cylinders.

Possible Answers:

Correct answer:

Explanation:

The volume of a cylinder is:

where is the radius of the circular end of the cylinder and is the height of the cylinder. So we can write:

 

We know that 

and 

.

 

So we can write:

Example Question #113 : Volume Of A Three Dimensional Figure

A cylinder has a diameter of  inches and a height of  inches. Find the volume, in cubic inches, of this cylinder.

Possible Answers:

 

 

 

 

Correct answer:

 

Explanation:

Since we are given the diameter, divide that value in half to find the radius.

 

Now plug this value into the equation for the volume of a cylinder.

 

 

Example Question #1993 : Hspt Mathematics

Find the volume, in cubic inches, of a cylinder that has a radius of  inches and a height of  inches.

Possible Answers:

 

 

 

 

Correct answer:

 

Explanation:

The formula to find the volume of a cylinder is .

Now, plug in the given numbers into this equation.

 

Example Question #731 : Geometry

Find the volume of the cylinder if the circular base has an area of , and the height of the cylinder is also 

Possible Answers:

Correct answer:

Explanation:

Write the formula for volume of a cylinder.

Remember that area of a circle is  

Since the area of the circle is known, substitute the area into the formula.

Example Question #175 : Geometry

A car dealership wants to fill a large spherical advertising ballon with helium. It can afford to buy 1,000 cubic yards of helium to fill this balloon. What is the greatest possible diameter of that balloon (nearest tenth of a yard)?

Possible Answers:

Correct answer:

Explanation:

The volume of a sphere, given its radius, is 

Set , solve for , and double that to get the diameter.

The diameter is twice this, or 12.4 yards.

Example Question #176 : Geometry

The diameter of a sphere is . Give the volume of the sphere in terms of .

Possible Answers:

Correct answer:

Explanation:

The diameter of a sphere is  so the radius of the sphere would be 

 

The volume enclosed by a sphere is given by the formula:

 

 

 

Example Question #177 : Geometry

A spherical balloon has a diameter of 10 meters. Give the volume of the balloon.

Possible Answers:

Correct answer:

Explanation:

The volume enclosed by a sphere is given by the formula:

where  is the radius of the sphere. The diameter of the balloon is 10 meters so the radius of the sphere would be meters. Now we can get:

 

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