Direct & Inverse Variation

The volume V of a gas kept at a constant temperature varies inversely as the pressure p.
If the pressure is 24 pounds per square inch, the volume is 15 cubic feet.
What will be the volume when the pressure is 30 pounds per square inch?

• 8 cubic feet

• 10 cubic feet

• 12 cubic feet

• 14 cubic feet

What relationship does the table represent?

• Direct

• Inverse

• Neither

In a direct variation, y=39 when x=3.  Find the value of y when x=2.

• 26

• 3

• 58.5

• 2

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

• 300

• 75

• 1,875

• 12

The number of kilograms of water in a person’s body varies directly as the person’s mass.  A person with a mass of 90 kg contains 60 kg of water.  How many kilograms of water are in a person whose mass is 75 kg?

• 50 kg water

• 72 kg water

• 94 kg water

• 150 kg water

What relationship does the table represent?

• Direct

• Inverse

• Neither

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

• y = 4x

• y = 144x

• y = 4/x

• y = 144/x

y varies directly as the square of x and indirectly with z. If y is 8 when x is 4 and z is 6, find y when x is 8 and z is 4.

• 3

• 12

• 48

• 64

Which of the following represents indirect variation?

• y = kx

• y = k/x

• y = x/k

• y = mx + b

If y = 15 when x = 12 find y when x = 32.

• 40

• -40

• 5

• -5