HiSET: Math : Use volume formulas to solve problems

Study concepts, example questions & explanations for HiSET: Math

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Example Questions

Example Question #1 : Cones

A cylinder has volume 120. A cone with base the same size as a base of the cylinder has the same height. Give the volume of the cone.

Possible Answers:

Insufficient information is given to answer the question.

Correct answer:

Explanation:

A cone with the same height as a given cylinder and a base the same radius as those of that cylinder has as its volume one-third that of the cylinder. That makes the volume of the cone one-third of 120, or

Example Question #3 : Cones

A right cone has height 10 and slant height 20. Which of the following correctly gives its volume? (Round to the nearest whole number).

Possible Answers:

Correct answer:

Explanation:

The volume of a cone, given radius and height , can be calculated using the formula

.

We are given that , but we are not given the value of . We are given that , and since the cone is a right cone, its radius, height, and slant height can be related using the Pythagorean relation

.

Substituting 10 for  and 20 for , we can find :

, which is what we need in the formula.

Now substitute in the volume formula:

This rounds to 3,142

Example Question #4 : Cones

A cone has as its base a circle whose radius is twice that of a base of a given cylinder; its height is 20% greater than that of the cylinder. Which of the following is true of the volume of the cone?

Possible Answers:

The volume of the cone is equal than that of the cylinder.

The volume of the cone is 20% greater than that of the cylinder.

The volume of the cone is 60% less than that of the cylinder.

The volume of the cone is 60% greater than that of the cylinder.

The volume of the cone is 20% less than that of the cylinder.

Correct answer:

The volume of the cone is 60% greater than that of the cylinder.

Explanation:

The volume of a cylinder with a base of radius and with height is

The cone has radius twice that of the cylinder, which is . Its height is 20% greater than, or 120% of, that of the cylinder, which is equal to .

 

The volume of a cone with a base of radius and height is

Set and :

Substitute  for :

.

This means that the volume of the cone is  times that of  the cylinder—or 60% greater.

Example Question #5 : Cones

About the -axis, rotate the triangle whose sides are along the -axis, the -axis, and the line of the equation

.

Give the volume of the solid of revolution formed.

Possible Answers:

None of the other choices gives the correct response.

Correct answer:

Explanation:

The vertices of the triangle are the points of intersection of the three lines. The -axis and the -axis meet at the origin .

The point of intersection of the -axis and the graph of —the -intercept of the latter—can be found by substituting 0 for :

Divide both sides by 2 to isolate :

The point of intersection is at .

Similarly, the point of intersection of the -axis and the graph of —the -intercept of the latter—can be found by substituting 0 for :

The point of intersection is at .

 

The three vertices of the triangle are at the origin, , and . When this triangle is rotated about the -axis, the resulting solid of revolution is a cone whose base has radius , and which has height . Substitute these values into the formula for the volume of a cone:

 

Example Question #2 : Cones

A right cone has height 20; its base has radius 10. Which of the following correctly gives its volume? (Round to the nearest whole number).

Possible Answers:

Correct answer:

Explanation:

The volume of a cone, given radius and height , can be calculated using the formula

.

We are given that and , so we can substitute and calculate:

To the nearest whole, this is 2,094.

Example Question #7 : Cones

A cone has as its base a circle whose radius is 20% greater that of a base of the cylinder; its height is twice that of the cylinder. Which of the following is true of the volume of the cone?

Possible Answers:

The volume of the cone is 4% less than that of the cylinder.

The volume of the cone is 52% less than that of the cylinder.

The volume of the cone is equal than that of the cylinder.

The volume of the cone is 52% greater than that of the cylinder.

The volume of the cone is 4% greater than that of the cylinder.

Correct answer:

The volume of the cone is 4% less than that of the cylinder.

Explanation:

The volume of a cylinder with a base of radius and with height is

The cone has height twice that of the cylinder, which is . Its radius is 20% greater than, or 120% of, that of the cylinder, which is equal to .

The volume of a cone with a base of radius and height is

Set  and :

Substitute  for :

This means that the volume of the cone is  that of the cylinder—or   less.

Example Question #11 : Cones

About the y-axis, rotate the triangle formed with the x-axis, the y-axis, and the line of the equation

.

Give the volume of the solid of revolution formed.

Possible Answers:

None of the other choices gives the correct response.

Correct answer:

Explanation:

The vertices of the triangle are the points of intersection of the three lines. The -axis and the -axis meet at the origin .

The point of intersection of the -axis and the graph of - the -intercept of the latter - can be found by substituting 0 for :

Divide both sides by 2 to isolate :

The point of intersection is at .

Similarly, The point of intersection of the -axis and the graph of - the -intercept of the latter - can be found by substituting 0 for :

The point of intersection is at .

The three vertices of the triangle are at the origin, , and . When this triangle is rotated about the -axis, the resulting solid of revolution is a cone whose base has radius , and which has height . Substitute these values into the formula for the volume of a cone:

Example Question #181 : Hi Set: High School Equivalency Test: Math

A right cone has slant height 20; its base has radius 10. Which of the following gives its volume to the nearest whole number?

(Round to the nearest whole number).

Possible Answers:

Correct answer:

Explanation:

The volume of a cone, given radius and height , can be calculated using the formula

.

We are given that , but we are not given the value of . We are given slant height , and since the cone is a right cone, its radius, height, and slant height can be related using the Pythagorean relation

.

Substituting 10 for and 20 for , we can find :

Now substitute in the volume formula:

To the nearest whole, this is 1,814.

Example Question #13 : Cones

The volume of a cone is . Which of the following most closely approximates the radius of the base of the cone if its height is ?

Possible Answers:

Correct answer:

Explanation:

The volume of a cone is given by the formula 

We are given that . Thus, the volume of our cone is given by

.

We are given that the volume of our cone is .

Thus,

so

and

.

Thus, 

.

so the correct answer is .

 

Example Question #1 : Spheres

The surface area of a sphere is equal to . Give the volume of the sphere.

Possible Answers:

Correct answer:

Explanation:

The surface area of a sphere can be calculated using the formula

Solving for :

Set and divide both sides by :

Take the square root of both sides:

Set in the volume formula:

,

the correct response.

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