Direct, Joint and Inverse Variation

Which table is an example of Inverse Variation?

• 
• 
• 
• 

The data shown in the table is best described as

• Inverse Variation

• Direct Variation

• Neither

• Joint Variation

Suppose that x and y vary inversely. Write a function that models each inverse variation if x = 6 when y = 2.

• y = 12 / x

• y = x / 12

• y = 3 / x

• y = x / 3

Write a function that models for the following situation; z varies jointly with x and y and inversely with w.

• z = (kxy) / w

• z = (xy) / w

• z = (kx) / yw

• z = (k) / xyw

Each pair of values if from a direct variation. Find the missing value.

(4, 10) , (8, y)

• 20

• 2.5

• 5 / 2

• 5

Each ordered pair is from an inverse variation. Find the constant of variation.

(5, 10)

• 50

• 1 / 2

• 2

• 25

Fundraising In a bake sale, you recorded the number of muffins sold and the amount of sales in a table as shown.

What is a function that relates the sales and the number of muffins?

• s = 2.5m

• s = 3m

• s = 192m

• Direct Variation

Fundraising In a bake sale, you recorded the number of muffins sold and the amount of sales in a table as shown.

How many muffins would you have to sale to make at least $250.00?

• 83

• 84

• 100

• 192

Painting The number of buckets of paint n needed to paint a fence varies directly with the total area a of the fence and inversely with the amount of paint p in a bucket. It takes three 1-gallon buckets of paint to paint 84 square feet of fence. How many 1-gallon buckets will be needed to paint 120 square feet of fence?

• 4

• 36

• 5

• 17

Potential Energy On Earth with a gravitational acceleration g, the potential energy stored in an object varies directly with its mass m and its vertical height h.

What is an equation that models the potential energy of a 3-kg skateboard that is sliding down a ramp?

• PE = gmh

• PE = mh

• PE = 3gh

• PE = g2h