Direct Variation and Proportionality

The value of y varies directly with x.  Which function represents the relationship between x and y if y = 20/3 when x = 30?

• y = 200x

• y = 2/9x

• y = 110/3x

• y = 9/2x

• A

• B

• C

• D

Mathematical Equivalence

ON

The value of y varies directly with x.  Which function represents the relationship between x  and y if y = 20/3  when x = 30?  

• y = 200x

• y = 2/9x

• y = 110/3x

• y = 9/2x

Write the equation for the table given.

• y = 1/3x

• y = 3x

• y = 1/2x

 y varies directly with x, and y is 84 when x is 16. What is the constant of proportionality?

• y = (21/4)x

• k= 21

• k= 5.25

• k= 4/21

Is the given table a direct variation? If so, what is the constant?

• Yes; 1/4

• Yes; 4

• Yes; 2

• No

Find the unit rate:  $3.60 for 3 pounds of apples. How much does it cost for 1 pound of apples?

• $1.00 per pound

• $3.60 per pound

• $1.20 per pound

• $1.10 per pound

What is the constant of proportionality?

• 8

• 16

• 24

• 2

Which graph shows a proportional relationship between x and y?

• A

• B

• C

• D