HiSET: Math : Measurement and Geometry

Study concepts, example questions & explanations for HiSET: Math

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Example Questions

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.

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

A sphere has surface area . Give its volume.

Possible Answers:

Correct answer:

Explanation:

The surface area of a sphere, given its radius , is equal to

Substitute for and solve for :

Divide by :

Extract the square root:

Substitute for in the volume formula:

,

the correct response.

Example Question #1 : Apply Concepts Of Density In Modeling Situations

A farmer has to make a square pen to hold chickens. If each chicken has to have  of area to roam and there are  chickens total, what is the length of the amount of fencing required to pen in the chickens?

Possible Answers:

Correct answer:

Explanation:

A square has area formula

 

The total area required for the chickens will be

since each chicken requires  of space and there are  chickens.

Thus, we have

for the length of our chicken fence.

Since there are four sides of a square and each side has a length of 5, the total length of fence required is

.

Example Question #1 : Apply Concepts Of Density In Modeling Situations

Census

Source: United States Census Bureau

The average population density of a geographic area is defined to be the average number of residents per square mile.

Above is a table with the land areas and populations of five states.Which state among the five has the greatest population density?

Possible Answers:

Kentucky

Mississippi

Arkansas

Tennessee

Alabama

Correct answer:

Tennessee

Explanation:

For each state, divide the population by the land area. We can round each figure to the nearest whole for simplicity's sake.

Alabama:

 persons per square mile.

Arkansas:

 persons per square mile.

Kentucky:

 persons per square mile.

Mississippi:

 persons per square mile.

Tennessee:

 persons per square mile.

Tennessee has the greatest population density among the five states. 

Example Question #3 : Apply Concepts Of Density In Modeling Situations

Census

Source: United States Census Bureau

The average population density of a geographic area is defined to be the average number of residents per square mile.

Above is a table with the population densities and the land areas of five states. Of the five, which state has the greatest population?

Possible Answers:

South Dakota

North Dakota

Vermont

Wyoming 

Alaska

Correct answer:

South Dakota

Explanation:

Multiply the population density of each state by its corresponding area to get an estimate of the population (round to the nearest thousand for simplicity's sake):

Alaska:

North Dakota:

South Dakota:

Vermont:

Wyoming:

Of the five states, South Dakota is the most populous.

Example Question #1 : Apply Concepts Of Density In Modeling Situations

County 1

The average population density of a geographic area is defined to be the average number of residents per square mile.

Above is the map of a county whose population is about 120,000. Which of the following is the best estimate of the average population density?

Possible Answers:

150 persons per square mile

50 persons per square mile

100 persons per square mile

200 persons per square mile

250 persons per square mile

Correct answer:

100 persons per square mile

Explanation:

The county is in the shape of a trapezoid with bases of length  and , and with height . Its area in square miles can be found by substituting in the formula for the area of a trapezoid:

 square miles

Divide the population by this area to obtain an estimate of the population density:

 persons per square mile.

Of the given choices, 100 persons per square mile comes closest.

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