# Lesson 20

The Volume of a Sphere

### Problem 1

1. A cube’s volume is 512 cubic units. What is the length of its edge?

2. If a sphere fits snugly inside this cube, what is its volume?

3. What fraction of the cube is taken up by the sphere? What percentage is this? Explain or show your reasoning.

### Problem 2

Sphere A has radius 2 cm. Sphere B has radius 4 cm.

1. Calculate the volume of each sphere.
2. The radius of Sphere B is double that of Sphere A. How many times greater is the volume of B?

### Problem 3

Three cones have a volume of $$192\pi$$ cm3. Cone A has a radius of 2 cm. Cone B has a radius of 3 cm. Cone C has a radius of 4 cm. Find the height of each cone.

### Solution

(From Unit 5, Lesson 16.)

### Problem 4

The graph represents the average price of regular gasoline in the United States in dollars as a function of the number of months after January 2014.

1. How many months after January 2014 was the price of gas the greatest?
2. Did the average price of gas ever get below \$2?
3. Describe what happened to the average price of gas in 2014.

### Solution

(From Unit 5, Lesson 5.)

### Problem 5

Match the description of each sphere to its correct volume.