SAT II Math I : 3-Dimensional Geometry

Study concepts, example questions & explanations for SAT II Math I

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Example Questions

Example Question #91 : Geometry

What is the volume of a regular tetrahedron with an edge length of 6?

Possible Answers:

Correct answer:

Explanation:

The volume of a tetrahedron can be solved for by using the equation:

where  is the measurement of the edge of the tetrahedron. 

This problem can be quickly solved by substituting 6 in for

Example Question #81 : Advanced Geometry

What is the volume of the tetrahedron shown below? 


Screen shot 2015 10 21 at 7.16.10 pm

Possible Answers:

Correct answer:

Explanation:

The volume of a tetrahedron is .

This tetrahedron has a side with a length of 8. 

, which becomes .

You can reduce that answer further, so that it becomes 

Example Question #21 : Volume

Find the volume of sphere whose radius is 15.

Possible Answers:

Correct answer:

Explanation:

The volume of a sphere is given by the equation:

The problem says that the radius is 15, so plug in 15 for r and simplify.

Example Question #101 : Geometry

Find the volume of a sphere with the diameter of .

Possible Answers:

Correct answer:

Explanation:

Write the equation for the volume of a sphere.

The radius is half the diameter, or .

Substitute the radius into the equation.

Reduce the fractions.

The answer is:  

Example Question #21 : 3 Dimensional Geometry

Determine the volume of a rectangular prism if the length is , width is , and the height is .

Possible Answers:

 

Correct answer:

 

Explanation:

Write the formula for the volume of a rectangular prism.

Substitute the dimensions into the formula.

Reduce this fraction.

The answer is:  

Example Question #21 : 3 Dimensional Geometry

The length of a box is half its height and two-thirds its width. The volume of the box is four cubic meters. Give the length of the box to the nearest centimeter.

Possible Answers:

None of these

Correct answer:

Explanation:

Call , and  the length, width, and height of the crate. 

The length of the crate is half its height, so 

The length of the crate is two-thirds its width, so

The dimensions of the crate in terms of  are , and . The volume is their product:

Substitute:

Solve for :

 meters.

Since one meter comprises 100 centimeters, multiply by 100 to convert to centimeters:

,

which rounds to 110 centimeters.

 

Example Question #1 : Surface Area

A circular swimming pool has diameter 32 meters and depth  meters throughout. Which of the following expressions gives the total area of the inside of the pool, in square meters?

Possible Answers:

None of the other responses is correct.

Correct answer:

Explanation:

The bottom of the pool is a circle with diameter 32, and, subsequently, radius half this, or 16; its area is

The side of the pool is the lateral surface of a cylinder with radius 16 and height ; the area of this is

The area of the inside of the pool is the sum of these two, or

Example Question #2 : Surface Area

A circular swimming pool at an apartment complex has diameter 50 feet and depth six feet throughout. 

The apartment manager needs to get the interior of the swimming pool painted. The paint she wants to use covers 350 square feet per gallon. How many one-gallon cans of paint will she need to purchase?

Possible Answers:

The correct answer is not given among the other responses.

Correct answer:

Explanation:

The pool can be seen as a cylinder with depth (or height) six feet and a base with diameter 50 feet - and radius half this, or 25 feet. 

The bottom of the pool - the base of the cylinder - is a circle with radius 25 feet, so its area is

 square feet.

Its side - the lateral face of the cylinder - has area

 square feet.

Their sum - the total area to be painted - is  square feet. Since one gallon of paint covers 350 square feet, divide:

Eight cans of paint and part of a ninth will be required, so the correct response is nine.

Example Question #1 : Surface Area

Example cylinder

Figure not drawn to scale.

Find the surface area of the cylinder above.

Possible Answers:

94.25 in2

73.44 in2

87.25 in2

122.14 in2

56.55 in2

Correct answer:

94.25 in2

Explanation:

In order to find the surface area of a cylinder, you need to find the surface areas of the circles that are the top and bottom of the cylinder (2 x pi x radius2) and add it to the surface are of the rectangle that is the side of the cylinder (diameter x height).

The surface area of the cylinder is 94.25 in2

Example Question #4 : Surface Area

Example images

Figure not drawn to scale

What is the surface area of the sphere above?

Possible Answers:

615.75 yd2

712.12 yd2

512.63 yd2

615.75 yd3

815.44 yd2

Correct answer:

615.75 yd2

Explanation:

Example images

In order to find the surface area of a sphere, you must use the equation below:

 

The surface area of the sphere is 615.75 yd2

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