SAT Math : Solid Geometry

Study concepts, example questions & explanations for SAT Math

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Example Questions

Example Question #121 : Solid Geometry

A sphere fits inside of a cube so that its surface barely touches each side of the cube at any given time. If the volume of the box is 27 cubic centimeters, then what is the volume of the sphere?  

Possible Answers:

None of the given answers. 

Correct answer:

Explanation:

If the volume of the cube is 27 cubic centimeters, then its height, width, and depth are all 3cm. Since the sphere fits perfectly in the cube, then the sphere's diameter is also 3. This means that its radius is .

Substitute this radius value into the equation for the volume of a sphere:

Example Question #811 : Geometry

The surface area of a sphere is 100. Give its volume. 

Possible Answers:

Correct answer:

Explanation:

The surface area  of a sphere is equal to 

,

where  is the radius.

Setting  and solving for :

Applying the Quotient of Radicals Rule:

The volume of the sphere can be determined from the radius using the formula

,

so, setting :

Applying the Quotient of Radicals Rule:

Rationalizing the denominator:

Example Question #41 : Spheres

 is a point on a sphere, and  is the point on the sphere farthest from . The shortest curve from  to  that is completely on the sphere is  in length. 

Give the volume of the sphere.

Possible Answers:

Correct answer:

Explanation:

The figure referenced is below.  is the center of the sphere.

Sphere

The shortest curve connecting  to its opposite point  is a semicircle. Also,  is a diameter of the sphere, and  and  are radii. 

Given radius , a semicircle has length

Setting  and solving for :

.

The volume of a sphere, given its radius , is

.

Setting :

 

Example Question #41 : Spheres

Find the volume of a sphere whose diameter is 10cm.

Possible Answers:

Correct answer:

Explanation:

Radius is half of the diameter. Half of 10cm is 5cm.

Example Question #12 : How To Find The Volume Of A Sphere

Spheres  element76

The radius of the sphere shown here is  long. What is its volume?

Possible Answers:

Correct answer:

Explanation:

The formula for the volume  of a sphere given its radius  is

The radius is stated to be  long; hence, we can calculate the sphere's volume by substituting this value for  into the formula, as shown:

Hence, the volume of the sphere is 

 

Example Question #1 : How To Find The Volume Of A Cylinder

The volume of a cylinder is 36π. If the cylinder’s height is 4, what is the cylinder’s diameter? 

Possible Answers:

4

9

6

12

3

Correct answer:

6

Explanation:

Volume of a cylinder? V = πr2h. Rewritten as a diameter equation, this is:

V = π(d/2)2h = πd2h/4

Sub in h and V: 36p = πd2(4)/4 so 36p = πd2

Thus d = 6

Example Question #1 : How To Find The Volume Of A Cylinder

A cylinder has a height of 5 inches and a radius of 3 inches.  Find the lateral area of the cylinder.

Possible Answers:

30π

45π

24π

8π

15π

Correct answer:

30π

Explanation:

LA = 2π(r)(h) = 2π(3)(5) = 30π

Example Question #1 : How To Find The Volume Of A Cylinder

A cylinder has a volume of 20. If the radius doubles, what is the new volume?

Possible Answers:

60

40

20

100

80

Correct answer:

80

Explanation:

The equation for the volume of the cylinder is πr2h. When the radius doubles (r becomes 2r) you get π(2r)2h = 4πr2h. So when the radius doubles, the volume quadruples, giving a new volume of 80.

Example Question #1 : How To Find The Volume Of A Cylinder

A cylinder has a height that is three times as long as its radius. If the lateral surface area of the cylinder is 54π square units, then what is its volume in cubic units?

Possible Answers:

27π

81π

243π

54π

Correct answer:

81π

Explanation:

Let us call r the radius and h the height of the cylinder. We are told that the height is three times the radius, which we can represent as h = 3r. 

We are also told that the lateral surface area is equal to 54π. The lateral surface area is the surface area that does not include the bases. The formula for the lateral surface area is equal to the circumference of the cylinder times its height, or 2πrh. We set this equal to 54π,

2πrh = 54π

Now we substitute 3r in for h.

2πr(3r) = 54π

6πr2 = 54π

Divide by 6π

r2 = 9.

Take the square root.

r = 3. 

h = 3r = 3(3) = 9.

Now that we have the radius and the height of the cylinder, we can find its volume, which is given by πr2h.

V = πr2h

V = π(3)2(9) = 81π

The answer is 81π.

Example Question #821 : Sat Mathematics

What is the volume of a hollow cylinder whose inner radius is 2 cm and outer radius is 4 cm, with a height of 5 cm?

Possible Answers:

20π cm3

60π cm3

80π cm3

50π cm3

100π cm3

Correct answer:

60π cm3

Explanation:

The volume is found by subtracting the inner cylinder from the outer cylinder as given by V = πrout2 h – πrin2 h. The area of the cylinder using the outer radius is 80π cm3, and resulting hole is given by the volume from the inner radius, 20π cm3. The difference between the two gives the volume of the resulting hollow cylinder, 60π cm3.

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