A.2D Direct Variation

A recipe for 3 dozen cookies calls for 4 cups of flour. The number of cookies is directly proportional to the amount of flour used. Write a direct variation equation for the relationship between the number of cookies and the number of cups of flour needed. Then find the number of cups of flour needed for 9 dozen cookies.

• 12 cups

• 9 cups

• 6 cups

• 3 cups

The cost of mailing a package is directly proportional to the weight of the package. It costs $8.75 to mail a 5lb package. Write a direct variation equation for the relationship between the cost of mailing a package and the weight of a package. Then find the cost for mailing a 12lb package.

• $21.00

• $18.75

• $15.00

• $10.50

Match the following values of x with their corresponding values of y, given that y varies directly as x and y = 65 when x = 13.

• x = 26

• 130

• x = 24

• 140

• x = 22

• 110

• x = 28

• 120

If y varies directly as x, and y = 3/2 when x = 9, write a direct variation equation that relates the two variables. Then find the value of y when x = 66.

• 11

• 22

• 33

• 44

If y varies directly as x, and y = 14 when x = 35, write a direct variation equation that relates the two variables. Then find the value of x when y = 22.

• 55

• 45

• 35

• 25

A brick layer can lay 57 bricks in 95 minutes. The number of bricks laid is directly proportional to the amount of time. Write a direct variation equation that models the relationship between the number of bricks laid and the amount of time spent laying the bricks. Then determine the amount of time it would take to lay 1200 bricks: (a)  

• 2000 minutes
• 1500 minutes
• 1000 minutes
• 800 minutes

An equation of direct variation can be written in the form: y = kx

• True

• False

Tags

CCSS.8.EE.B.6

CCSS.8.F.B.4

Select all the equations that represent a direct variation:

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• 
• 

Tags

CCSS.8.EE.B.5

CCSS.8.EE.B.6

CCSS.8.F.A.3

CCSS.8.F.B.4

The variables x and y vary directly. Choose the correct direct variation equation that relates x and y.

y = 15; x = 3

A computer printer can print 3 pages in 25 seconds. Which proportion can be used to find x, the time it will take the printer to print 10 pages?