Direct and Inverse Variation

y varies directly as x. If y = 15 when x = 12 find y when x = 32.

• 40

• -40

• 5

• -5

The width of a rectangle varies inversely with its length. If the width is 6 (x) when the length is 24 (y), give an equation that shows the relationship.

• y = 4x

• y = 144x

• y = 4/x

• y = 144/x

The height of a wave on the Atlantic Ocean varies directly with the seconds that pass by. At 4 seconds (y), the wave is 6 feet high (x). How many seconds will give you a wave that is 10 feet high?

• y = 2/3x

• 6

• 6.6

• 7

y varies inversely with x, and y is 0.5 when x is 4. Which equation represents this situation?

• y = 2x

• y = 2/x

• y = 4x

• y = x/2

Suppose y varies inversely with x.
If y = 150 when x = 2, find y when x = 25.

• 300

• 75

• 1,875

• 12

Given that y varies inversely with x, if x =7 and y = 4, what is y when x = 2?

• 14

• 10

• 2

• -14

• direct variation
• inverse variation
• neither direct nor inverse variation

Write an equation for this relationship.

• y=4x

• y=1/8x

• y=1/4x

• y=8x

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

• Yes; 1/4

• Yes; 4

• Yes; 2

• No

Is this a direct variation?
y=2x

• yes

• no